Java Padawan on J2ME and Android

Android Custom Database ListAdapters

2012-01-05T05:46:00.004+08:00

On the ListActivity class :


ListPatientCursorAdapter listAdapter = new ListPatientCursorAdapter(this, R.layout.patient_list, cursor);
setListAdapter(listAdapter);
startManagingCursor(cursor);

Custom List Adapter :


 class ListPatientCursorAdapter extends ResourceCursorAdapter {
  
  public ListPatientCursorAdapter(Context context, int layout, Cursor c) {
   super(context, layout, c);
  }

  @Override
  public View newView(Context context, Cursor cur, ViewGroup parent) {
   LayoutInflater li = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
   return li.inflate(R.layout.patient_list_row, parent, false);
  }
  
  
  @Override
  public void bindView(View v, Context context, final Cursor _c) {
   TextView tvId = (TextView)v.findViewById(R.id.tvId);
   final Integer id = _c.getInt(_c.getColumnIndex(Patient.PatientField.ID));
   TextView tvFirstName = (TextView) v.findViewById(R.id.tvFirstName);
   tvFirstName.setText(_c.getString(_c
     .getColumnIndex(Patient.PatientField.FIRSTNAME)));

   TextView tvMiddleName = (TextView) v
     .findViewById(R.id.tvMiddleName);
   tvMiddleName.setText(_c.getString(_c
     .getColumnIndex(Patient.PatientField.MIDDLENAME)));

   TextView tvLastName = (TextView) v.findViewById(R.id.tvLastName);
   tvLastName.setText(_c.getString(_c
     .getColumnIndex(Patient.PatientField.LASTNAME)));

   TextView tvLastUpdate = (TextView) v
     .findViewById(R.id.tvLastUpdate);
   
   CheckBox cbFollowUp = (CheckBox) v.findViewById(R.id.cbFollowUp);
   cbFollowUp
     .setChecked(_c.getInt(_c
       .getColumnIndex(Patient.PatientField.FOR_FOLLOWUP)) == 0 ? false
       : true);
   
   Calendar cal = Calendar.getInstance();
   cal.setTimeInMillis(_c.getLong(_c
     .getColumnIndex(Patient.PatientField.UPDATE_DATE)));
   
   tvLastUpdate.setText(sdf.format(cal.getTime()));
  
   v.setOnClickListener(new OnClickListener() {
    public void onClick(View v) {
     processSelectedId(id);
    }
   });
  }
 }

List View :


            android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >
                    android:id="@android:id/list"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:divider="#FFFFFF"
            android:dividerHeight="0sp"
            android:scrollbars="none" />
                    android:id="@id/android:empty"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_margin="5px"
            android:gravity="center"
            android:text="No Patient Record." >

List Row :



    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
                    android:id="@+id/tvId"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=""
            android:visibility="gone"/>
            android:id="@+id/llPatient"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >
                    android:id="@+id/tvLastName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Puti"
            android:textAppearance="?android:attr/textAppearanceLarge" />
                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" "
            android:textAppearance="?android:attr/textAppearanceMedium" />
                    android:id="@+id/tvFirstName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Kyle"
            android:textAppearance="?android:attr/textAppearanceMedium" />

                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" "
            android:textAppearance="?android:attr/textAppearanceMedium" />

                    android:id="@+id/tvMiddleName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Amousy"
            android:textAppearance="?android:attr/textAppearanceMedium" />
    
            android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >
                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Last Update"
            android:textAppearance="?android:attr/textAppearanceMedium" />
                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" "
            android:textAppearance="?android:attr/textAppearanceMedium" />
                    android:id="@+id/tvLastUpdate"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Last Update" />
    
            android:id="@+id/cbFollowUp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"
        android:enabled="false"
        android:text="For Follow Up" />

Android SQLite Primary Key Auto Increment

2012-01-05T04:38:00.008+08:00

WRONG :

CREATE TABLE PERSON (ID INTEGER PRIMARY KEY AUTOINCREMENT,
FIRSTNAME TEXT,
LASTNAME TEXT)

WRONG :

CREATE TABLE PERSON (ID INT PRIMARY KEY AUTOINCREMENT,
FIRSTNAME TEXT,
LASTNAME TEXT)

CORRECT :

CREATE TABLE PERSON (ID INTEGER PRIMARY KEY,
FIRSTNAME TEXT,
LASTNAME TEXT)

Java Code To Insert (Do Not Set ID field):

ContentValues values = new ContentValues();
values.put("FIRSTNAME", "Java");
values.put("LASTNAME", "Padawan");

Then on your SQLiteDatabase instance do :

sqlDatabase.insert("PERSON" null, values);

Android Parsing JSON

2009-08-10T15:56:00.007+08:00

1. Parse the live JSON response from http://beer.androidph.com/beerws. See App Engine Generating JSON.

2. Use the code from Android Networking Tutorial

3. JSON Parser Code



JSONArray parseArray = new JSONArray(message);
for (int i = 0; i < jo =" parseArray.getJSONObject(i);

4. Modify nextscreen.xml of the source code from #2.

5. Modify NextScreen.java from source code in #2 or Android Networking Tutorial


public class NextScreen extends Activity implements OnClickListener {
 private Button btnBack;

 private ViewGroup.LayoutParams layoutName;
 private ViewGroup.LayoutParams layoutAddress;
 private ViewGroup.LayoutParams layoutPrice;
 private ViewGroup.LayoutParams layoutLastCallTime;
 private ViewGroup.LayoutParams layoutLocation;

 private String message;
 private LinearLayout linearLayout;
 private LinearLayout linearInnerLayout;

 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.nextscreen);
  initComponents();
 }

 public void initComponents() {

  linearLayout = (LinearLayout) findViewById(R.id.linearLayout);
  linearInnerLayout = (LinearLayout) linearLayout.getChildAt(0);

  layoutName = ((TextView) linearInnerLayout.getChildAt(0))
    .getLayoutParams();
  layoutAddress = ((TextView) linearInnerLayout.getChildAt(1))
    .getLayoutParams();
  layoutPrice = ((TextView) linearInnerLayout.getChildAt(2))
    .getLayoutParams();
  layoutLastCallTime = ((TextView) linearInnerLayout.getChildAt(3))
    .getLayoutParams();
  layoutLocation = ((TextView) linearInnerLayout.getChildAt(4))
    .getLayoutParams();

  message = getIntent().getStringExtra(NetworkConnection.NC_RESPONSE);
  
  LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
    LinearLayout.LayoutParams.FILL_PARENT,
    LinearLayout.LayoutParams.WRAP_CONTENT);
  
  try {
   JSONArray parseArray = new JSONArray(message);
   for (int i = 0; i < parseArray.length(); i++) {
    JSONObject jo = parseArray.getJSONObject(i);
    
    LinearLayout newRow = new LinearLayout(this);
    newRow.setLayoutParams(linearInnerLayout.getLayoutParams());
    
    String name = jo.getString("name") + " | ";
    TextView curTvName = new TextView(this);
    curTvName.setText(name);
    curTvName.setLayoutParams(layoutName);
    
    String address = jo.getString("address") + " | ";
    TextView curTvAddress = new TextView(this);
    curTvAddress.setText(address);
    curTvAddress.setLayoutParams(layoutAddress);
    
    String price = jo.getString("price") + " | ";
    TextView curTvPrice = new TextView(this);
    curTvPrice.setText(price);
    curTvPrice.setLayoutParams(layoutPrice);
    
    String lastCallTime = jo.getString("lastCallTimeString") + " | ";
    TextView curTvLastCallTime = new TextView(this);
    curTvLastCallTime.setText(lastCallTime);
    curTvLastCallTime.setLayoutParams(layoutLastCallTime);
    
    String location = jo.getString("latitude") + "," + jo.getString("longitude");
    TextView curTvLocation = new TextView(this);
    curTvLocation.setText(location);
    curTvLocation.setLayoutParams(layoutLocation);
    
    newRow.addView(curTvName);
    newRow.addView(curTvAddress);
    newRow.addView(curTvPrice);
    newRow.addView(curTvLastCallTime);
    newRow.addView(curTvLocation);
    
    linearLayout.addView(newRow, new LinearLayout.LayoutParams(
      LinearLayout.LayoutParams.FILL_PARENT,
      LinearLayout.LayoutParams.WRAP_CONTENT));
   }
  } catch (JSONException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }

 @Override
 public void onClick(View v) {
  if (v == btnBack) {
   finish();
  }
 }
}

6. Screenshot of the android JSON parser.

Generating JSON with Java App Engine

2009-08-07T15:44:00.004+08:00

1. Requirements App Engine 1.2.2. (The older version of App Engine has a problem compiling the org.json package)

2. Download Java JSON.zip from http://www.json.org

3. Read my first app engine tutorial.

4. Generate a JSON string from any java.util.List of Objects. For this instance I used the objects from #3.


public class BeerWS extends HttpServlet {

 public void process(HttpServletRequest req, HttpServletResponse resp)
   throws IOException, ServletException {
  resp.setContentType("text/plain");
     PersistenceManager persistenceManager = PMF.get()
  .getPersistenceManager();
  String query = "select from " + Beer.class.getName()
  + " order by name asc";
  List beerLocations = (List)persistenceManager.newQuery(query).execute();
  List list = new ArrayList();
  for(Beer beer : beerLocations) {
   //Add the pojo as a JSONObject
   list.add(new JSONObject(beer));
  }
  //Create a JSONArray based from the list of JSONObejcts
  JSONArray jsonArray = new JSONArray(list);
  //Then output the JSON string to the servlet response
  resp.getWriter().println(jsonArray.toString());
 }

 public void doPost(HttpServletRequest req, HttpServletResponse resp)
   throws IOException, ServletException {
  process(req, resp);
 }

 public void doGet(HttpServletRequest req, HttpServletResponse resp)
   throws IOException, ServletException {
  process(req, resp);
 }
}

5. Here's the link of the live demo. http://beer.androidph.com/beerws. Below is the object used if you have not already check my previous app engine tutorial.


@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Beer {
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
 private Long id;
    @Persistent
 private String name;
    @Persistent
 private Double price;
    @Persistent
 private Date lastCallTime;
    @Persistent
 private String promotions;
    @Persistent
 private String address;
    @Persistent
 private Double longitude;
    @Persistent
 private Double latitude;

    public Beer() {}
    
    public Beer(String name, Double price, 
      Date lastCallTime, String promotions, 
  String address, Double longitude, Double latitude) {
     this.name = name;
     this.price = price;
     this.lastCallTime = lastCallTime;
     this.promotions = promotions;
     this.address = address;
     this.longitude = longitude;
     this.latitude = latitude;
    }
    
    public Beer(Long id, String name, Double price, 
      Date lastCallTime, String promotions, String address, 
     Double longitude, Double latitude) {
     this.id = id;
     this.name = name;
     this.price = price;
     this.lastCallTime = lastCallTime;
     this.promotions = promotions;
     this.address = address;
     this.longitude = longitude;
     this.latitude = latitude;
    }
 public Long getId() {
  return id;
 }
 public void setId(Long id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public Double getPrice() {
  return price;
 }
 public void setPrice(Double price) {
  this.price = price;
 }
 public Date getLastCallTime() {
  return lastCallTime;
 }
 public void setLastCallTime(Date lastCallTime) {
  this.lastCallTime = lastCallTime;
 }
 private SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
 public String getLastCallTimeString() {
  if(lastCallTime != null) {
   return sdf.format(lastCallTime);
  } else {
   return "-";
  }
 }
 public String getPromotions() {
  return promotions;
 }
 public void setPromotions(String promotions) {
  this.promotions = promotions;
 }
 public String getAddress() {
  return address;
 }
 public void setAddress(String address) {
  this.address = address;
 }
 public Double getLongitude() {
  return longitude;
 }
 public void setLongitude(Double longitude) {
  this.longitude = longitude;
 }
 public Double getLatitude() {
  return latitude;
 }
 public void setLatitude(Double latitude) {
  this.latitude = latitude;
 }
}

Google App Engine - Spring Integration Issues

2009-07-21T17:54:00.008+08:00

I'm currently building the server component of Beer Radar using Google App Engine and Spring Framework 3.0.

I've encountered these problems below and posting their corresponding solutions.

Problem:
Google App Engine cannot read JSTL and Spring Expression on JSPs

Solution:
Google App Engine has isELIgnored="true" by default.
Just add the isELIgnored="false" on the <%@page section in the JSP.

Problem:
org.springframework.web.servlet.tags.RequestContextAwareTag doStartTag: access denied (java.lang.RuntimePermission getClassLoader)

Solution:
Add the following on your Controller

For Annotated controllers use
@InitBinder
public void initLogin(WebDataBinder binder) {
System.out.println("initLogin");
binder.registerCustomEditor(String.class, new StringTrimmerEditor
(false));
}

For sub-classed controllers
Override the InitBinder method and register string trimmed editor in the binder
binder.registerCustomEditor(String.class, new StringTrimmerEditor
(false));

Problem:
org.springframework.web.HttpSessionRequiredException: Session attribute '' required - not found in session

and/or

Uncaught exception from servlet
java.lang.RuntimeException: java.io.NotSerializableException:

Solution :
implements Serializable {
private static final long serialVersionUID = <generated value>L

The unserialized Session object will work on development but, it will throw a java.io.NotSerializableException on the appspot server.

Problem :
Attempt was made to manually set the id component of a Key primary key. If you want to control the value of the primary key, set the name component instead.

Solution :
This happens when I update a child object. The solution for this, is to re-attach the parent object first, by
Parent attached = pm.getObjectById(Parent.class, detachedParent.getId());
then
Modify the child
attached.getChild().setName("new value");
then
pm.makePersistent(attachedDrunkard);

This solved the problem for me. Here's a link of a couple of alternative solutions.

App Engine Tutorial : Creating the Beer Radar Server component

2009-04-14T17:58:00.013+08:00

App Engine App #1.0 - Server Component for Android Application Beer Radar.

I created the Beer Radar Android Application last February 2009, and I was looking for a suitable Java server application. I don't know when it was announced, but I just heard about the Google App Engine support for Java last week (April 10, 2009).

Here's the basic App Engine Application which I'll connect the Beer Radar app soon. :) http://beer.androidph.com/

I quickly signed up to see what is it all about. So, here's what I learned so far.

Here are the steps to create a web app using Google App Engine with Java Lanuage Support.

1. Sign-up for an App Engine Account http://appengine.google.com/ you should click link for Java then click the sign-up button (I waited for 2 days for the confirmation). I don't have a screenshot for it, but its easy to spot.

2. Download the Google App Engine SDK http://code.google.com/appengine/downloads.html

3. Install the App Engine Eclipse Plugin
From the Eclipse Menu, go to HELP > Software Update...
Click the Available Software Tab
Click Add Site, type http://dl.google.com/eclipse/plugin/3.4
Then Install
See http://code.google.com/appengine/docs/java/tools/eclipse.html for more details.
Restart Eclipse

4. Click the New Web Application Icon as shown below

5. Type in the Project name and package. I unchecked the GWT option since I'm not going to use it.

6. Then click Finish. Everything is created for you, even the libraries that you need for your application.

7. Run the server by right-clicking on the project, select Debug As > Web Application

8. If you have tomcat running by default, you'd probably get this error message
WARNING: failed SelectChannelConnector@127.0.0.1:8080
java.net.BindException: Address already in use: bind

9. Fix this by going to the Debug Configurations, then on the Main Tab, set a new port or click "Automatically select an unused port".

10. Click Debug.

11. Now open your browser to http://localhost:8989.

12. Now you can test your application.

13. Once you're done with you application and you already got the Google confirmation message, you can now create an application.

14. Type in a unique Application Identifier and the Application Title. This will be used in deploying your application.

15. Once everything is done, you can now deploy by clicking the Deploy App Engine Project icon.

16. You will need to click the App Engine project settings to enter your Application Identifier.

17. Enter you Application ID then type in a version then click OK.

18. Enter your Google App Engine Account Email and Password and that is done.

20. Here's the app http://beerradar.appspot.com/ I deployed, to be used as the server component of the Beer Radar project.

21. AND YES, I had to put in the ads. ;)

What I really like about the app engine is the JDO support.

Here's the code for my Persistent Object
Beer.java


package com.androidph.beerserver;

import java.text.SimpleDateFormat;
import java.util.Date;

import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.IdentityType;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Beer {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Long id;

@Persistent
private String name;

@Persistent
private Double price;

@Persistent
private Date lastCallTime;

@Persistent
private String promotions;

@Persistent
private String address;

@Persistent
private Double longitude;

@Persistent
private Double latitude;

public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public Double getPrice() {
return price;
}

public void setPrice(Double price) {
this.price = price;
}

public Date getLastCallTime() {
return lastCallTime;
}

public void setLastCallTime(Date lastCallTime) {
this.lastCallTime = lastCallTime;
}

private SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");

public String getLastCallTimeString() {
if(lastCallTime != null) {
return sdf.format(lastCallTime);
} else {
return "-";
}
}

public String getPromotions() {
return promotions;
}

public void setPromotions(String promotions) {
this.promotions = promotions;
}

public String getAddress() {
return address;
}

public void setAddress(String address) {
this.address = address;
}

public Double getLongitude() {
return longitude;
}

public void setLongitude(Double longitude) {
this.longitude = longitude;
}

public Double getLatitude() {
return latitude;
}

public void setLatitude(Double latitude) {
this.latitude = latitude;
}

public String toString() {
return id + " | " + name + " | " + price + " | " + lastCallTime + " | " + promotions + " | " + address + " | " + longitude + " | " + latitude;
}

public byte[] convertToStream() {
return null;
}

public void fromStream(byte[] data) {

}
}

Here's the code to get a Persistence Manager. I got this from the GuestBook demo included in the AppEngine SDK

PMF.java


package com.androidph.beerserver;

import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManagerFactory;

public final class PMF {
private static final PersistenceManagerFactory pmfInstance =
JDOHelper.getPersistenceManagerFactory("transactions-optional");

private PMF() {}

public static PersistenceManagerFactory get() {
return pmfInstance;
}
}

Here are code snippets on how to use the Persistence Manager.

Persisting an Object


PersistenceManager persistenceManager = PMF.get()
.getPersistenceManager();
Beer beer = beerValidator.getBeer(name, address, price,
lastCallTime, promotions, longitude, latitude);
persistenceManager.makePersistent(beer);

Retrieving Data


String query = "select from " + Beer.class.getName()
+ " order by name asc";
List beerLocations = (List) persistenceManager
.newQuery(query).execute();
for (Beer beer : beerLocations) {
beerServletData.addLog("beer.toString() : " + beer.toString());
}

App #1.0 - Beer Radar

2009-02-08T11:32:00.011+08:00

I want to create an application, where it downloads bar location and some necessary details such as price of a beer, location and last call time. Also, I want it to be plotted with the user's current GPS location. Also, I want to have a server where user's can upload their recommended bars so that other user's may see it on their screens.

Download Source Code Below.

Objectives:
1. Download Bar Details from Server
* 2. Plot Bar Details with respect to the user's current gps location
3. Upload Bar Details to Server
4. Be able adjust the coverage of the radar (1 km - 10 km)

But for this tutorial, I just want to implement #2, since I still can't find a nice free server to host my server app.

The MODEL

STEP 1. Create BeerLocation.java
- this is just a POJO for the Bar Details. It also stores the longitude and latitude values of the Bar.


package com.androidph.beer.model;

import java.text.DecimalFormat;

public class BeerLocation {

private int id;
private String name;
private String price;
private String description;
private String lastCallTime;
private double latitude;
private double longitude;
private DecimalFormat df = new DecimalFormat("####.##");

public BeerLocation(String name, String price, String description,
String lastCallTime, double latitude, double longitude) {
this.name = name;
this.price = price;
this.description = description;
this.lastCallTime = lastCallTime;
this.latitude = latitude;
this.longitude = longitude;
}

public String toString() {
return name + ", " + price + " ( " + df.format(longitude) + ", " + df.format(latitude) + " ) ";
}

public BeerLocation() {
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getPrice() {
return price;
}

public void setPrice(String price) {
this.price = price;
}

public String getDescription() {
return description;
}

public void setDescription(String description) {
this.description = description;
}

public String getLastCallTime() {
return lastCallTime;
}

public void setLastCallTime(String lastCallTime) {
this.lastCallTime = lastCallTime;
}

public double getLatitude() {
return latitude;
}

public void setLatitude(double latitude) {
this.latitude = latitude;
}

public double getLongitude() {
return longitude;
}

public void setLongitude(double longitude) {
this.longitude = longitude;
}

}

STEP 2. Create interface BarLocationService.java
- contains the method to retrieve a List of Bar Details. Currently, the implementation is just hard-coded and will be replaced on the next iterationsof this application.


package com.androidph.beer.model;

import java.util.List;

public interface BeerLocationService {
public List retrieveAllBeerLocations();
}

STEP 3. Create BeerLocationServiceMemory.java
- Just create a java.util.List and add BeerLocation to the list.


package com.androidph.beer.model.impl;

import java.util.ArrayList;
import java.util.List;

import com.androidph.beer.model.BeerLocation;
import com.androidph.beer.model.BeerLocationService;

public class BeerLocationServiceMemory implements BeerLocationService {

private List beerLocations = new ArrayList();
@Override
public List retrieveAllBeerLocations() {
beerLocations.add( new BeerLocation("Chili Pepper's", "Php45.0", "", "9:00AM", 50, 50));
beerLocations.add( new BeerLocation("OTB", "Php45.0", "", "3:00AM", 0, 0));
beerLocations.add( new BeerLocation("Gerry's Grill", "Php38.0", "", "00:00AM", 235, 100));
beerLocations.add( new BeerLocation("Giligan's", "Php40.0", "", "03:00AM", 180, 150));
return beerLocations;
}
}

The VIEW

STEP 1. Create BeerRadarView
- Extend the android.view.View class. The View class contains the onDraw(Canvas) method which is where the painting is done. The onDraw(Canvas) method is similar to the paint(Graphics g) of AWT and/or Swing components. Even the draw methods are almost the same. (example. g.drawArc(...), canvas.drawArc(...), g.drawLine(...), canvas.drawLine(...) and so forth. The only difference is that the canvas stores most of its paint/draw properties in a Paint object.
- The Paint class stores common drawing properties such as color, font size, stoke etc.
- The coordinates are also the same for both canvas and graphics. 0,0 is the upperleft-most and MAX_WIDTH, MAX_HEIGHT is on the lower right-most.


@Override
protected void onDraw(Canvas canvas) {
if(!hasInitialized) {
initializeConstants();
}
drawRadarGrid(canvas);
drawRadar(canvas);
drawBeer(canvas, beerLocations);
String currentLocation = "( " + df.format(currentLongitude) + ", " + df.format(currentLatitude) + " )";
canvas.drawText(currentLocation, midpointX-30, midpointY-5, paintScreenText);
}

STEP 2. Drawing the Radar Grid
- Just plot two lines that looks like a corsair.

STEP 3. Drawing the Radar Circles
- This uses the canvas.drawCircle(...) which actually is not on the graphics class. The canvas.drawArc(...), is different from the drawCircle, since it uses a RectF to get the size of the arc/ellipse to be drawn.


private void drawRadarGrid(Canvas canvas) {
canvas.drawLine(0, midpointY, screenWidth, midpointY, paintRadarGrid);
canvas.drawLine(midpointX, 0, midpointX, screenHeight, paintRadarGrid);

STEP 4. Animated the Radar
- Use the circle path formula
x = A cos(radian);
y = A Sine(radian);
Where A is the amplitude.
- Since I am using 0-360 degrees for the angles, it is necessary to convert degrees to radians.
- Radian = Angle * (PI / 180)


private void drawRadar(Canvas canvas) {
if (startAngle > 360) {
startAngle = 0;
}
float x = (float) (minimumScreenSize / 2 * Math.cos(startAngle
* (Math.PI / 180)));
float y = (float) (minimumScreenSize / 2 * Math.sin(startAngle
* (Math.PI / 180)));
canvas.drawLine(getWidth() / 2, getHeight() / 2, x + getWidth() / 2, y
+ getHeight() / 2, paintRadar);
startAngle += 3;
}

STEP 5. Plotting the BeerLocation data.
- Plot the longitude and latitude of the BeerLocation with respect to the user's current GPS location
- x = (beerLoc.getLongitude() + midpointX - currentLongitude - BEER_ICON_SIZE);
Since the screens midpoint is not 0, the longitude must the adjusted. The + (positive) value of X should be in the WEST part of the screen. So the midpoint of the X-axis must be added to the location's longitude. Also, to adjust it to the user's current location, the currentLongitude is subtracted. The BEER_ICON_SIZE is subtracted just so it becomes centered.
- y = (midpointY - beerLoc.getLatitude() + currentLatitude - BEER_ICON_SIZE);
There's a slight difference between the computation of Y, since the + (positive) value of y should be on the NORTH part of the screen, thus, the point is adjusted. So, midpoint of Y is subtracted with the beer location's latitude. Also, the currentLatitude is added to the equation.
- The maximum coverage is not yet adjustable yet. In the future, I'll modify so that the user can select a minimum radius of 1KM and a maximum radius of 10KM. I currently do not know how each degrees of the longitude and latitude translates into KM. I'll research on it first.


private void drawBeer(Canvas canvas, List beerLocations) {
if(beerIcon == null) {
beerIcon = BitmapFactory.decodeResource(this.getResources(), R.drawable.beer);
}
for(BeerLocation beerLoc : beerLocations) {
float x =  (float)(beerLoc.getLongitude() + midpointX - currentLongitude - BEER_ICON_SIZE);
float y = (float)(midpointY - beerLoc.getLatitude() + currentLatitude - BEER_ICON_SIZE);
canvas.drawBitmap(beerIcon, x, y,  paintScreenText);
canvas.drawText(beerLoc.toString(), x, y,  paintScreenText);
}
}

The ACTIVITY
STEP 1. Set the BeerRadarView as the Activity's contentView


@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
beerRadarView = new BeerRadarView(this);
setContentView(beerRadarView);
setCurrentGpsLocation(null);
thread = new Thread(new MyThreadRunner());
thread.start();
}

STEP 2. Create a android.os.Handler that invalidate's the view when called. Invalidate is similar to calling awt/swing component's repaint() method.

"When a process is created for your application, its main thread is dedicated to running a message queue that takes care of managing the top-level application objects (activities, intent receivers, etc) and any windows they create. You can create your own threads, and communicate back with the main application thread through a Handler. This is done by calling the same post or sendMessage methods as before, but from your new thread. The given Runnable or Message will than be scheduled in the Handler's message queue and processed when appropriate."


Handler updateHandler = new Handler() {
/** Gets called on every message that is received */
// @Override
public void handleMessage(Message msg) {
switch (msg.what) {
case UPDATE_LOCATION: {
beerRadarView.setCurrentLatitude(latitude);
beerRadarView.setCurrentLongitude(longitude);
break;
}
}
beerRadarView.invalidate();
super.handleMessage(msg);
}
};

STEP 3. implement android.location.LocationListener on the Activity


public class BeerRadar extends Activity implements LocationListener {

- Implement the necessary methods.


@Override
public void onLocationChanged(Location location) {
setCurrentGpsLocation(location);
}

@Override
public void onProviderDisabled(String provider) {
setCurrentGpsLocation(null);

}

@Override
public void onProviderEnabled(String provider) {
setCurrentGpsLocation(null);
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
setCurrentGpsLocation(null);
}

- Use onLocationChanged(Location location) to update the user's current location


private void setCurrentGpsLocation(Location location) {
if (location == null) {
locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
locationManager.requestLocationUpdates(
 LocationManager.GPS_PROVIDER, 0, 0, this);
location = locationManager
 .getLastKnownLocation(LocationManager.GPS_PROVIDER);
}
longitude = location.getLongitude();
latitude = location.getLatitude();
Message msg = new Message();
msg.what = UPDATE_LOCATION;
BeerRadar.this.updateHandler.sendMessage(msg);
}

Testing

Since it just an emulator, you can use the DDMS perspective to update the longitude and latitude.Longitude =50, Latitude = 50

Longitude =120, Latitude = 100


Source Code

Android Camera Capture Tutorial

Reference: http://www.anddev.org/the_pizza_timer_-_threading-drawing_on_canvas-t126.html

Camera Capture

2008-11-24T00:52:00.016+08:00

Source code can be downloaded below.

Before creating the Image Capture application, the SDCard must be configured first in order to be able to save in the Picture Gallery of the emulator.

Creating the SDCARD

1. See the emulator -help-sdcard to see where the default sdcard.img is located. Create if necessary.

2. Type mksdcard in the command line to know the required switches in the command-line.

3. Make SD Card.

4. For my SD Card, I just went to the default folder on step#1 and created the default SD-Card.
-cd to the default sd directory
-mksdcard 16M sdcard.img

*Note: the minumum SD required by the emulator is 8Megabytes, I just used 16M to make sure. Also, the higher the size of the SD, the longer it takes to create. So, when you create a 4GB SD, the command line might seem unresponsive.

I've been trying to figure out how to capture images in android and storing it in the picture gallery for 2 weeks now.

I just discovered, that there is nothing wrong with the code, but there's something wrong with the emulator.

For one thing, I keep on getting this image, even when using the built in Camera Application on the main menu. But, I think it is normal. Is it?

The problem I am having is that when I capture an image in the application, the File Explorer (sdcard/dcim/Camera) does save the image file. But when I check the gallery, it does not seem to exist. I then try to push an image to the emulator's file system (sdcard/dcim/Camera), but still the Picture Gallery does not reflect. Below, is a screenshot of what (sdcard/dcim/Camera) contains and what shows in the emulator's picture gallery.

When I restarted the emulator, the Picture Gallery reflected the content's of the file system. Is this a bug or did I just missed a step?

Anyways, here's the code I compiled from various sources using Google Android SDK 1R1.

http://www.anddev.org/viewtopic.php?p=704#704
http://www.anddev.org/viewtopic.php?p=645#645

I also used another site but I forgot the link. So if you see your code here, just drop me a message and I'll link you up as reference. I think the file I downloaded was CameraTestApi.zip but was based on an older SDK. I apologize for the author of the code that I based my revised Image Capture application.

Here the code for the Image Capture Application.

1. Create two classes.
ImageCapture.java



public class ImageCapture extends Activity implements SurfaceHolder.Callback
{
private Camera camera;
private boolean isPreviewRunning = false;
private SimpleDateFormat timeStampFormat = new SimpleDateFormat("yyyyMMddHHmmssSS");

private SurfaceView surfaceView;
private SurfaceHolder surfaceHolder;
private Uri target = Media.EXTERNAL_CONTENT_URI;

public void onCreate(Bundle icicle)
{
super.onCreate(icicle);
Log.e(getClass().getSimpleName(), "onCreate");
getWindow().setFormat(PixelFormat.TRANSLUCENT);
setContentView(R.layout.main);
surfaceView = (SurfaceView)findViewById(R.id.surface);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public boolean onCreateOptionsMenu(android.view.Menu menu) {
MenuItem item = menu.add(0, 0, 0, "goto gallery");
item.setOnMenuItemClickListener(new MenuItem.OnMenuItemClickListener() {
 public boolean onMenuItemClick(MenuItem item) {
     Intent intent = new Intent(Intent.ACTION_VIEW, target);
     startActivity(intent);
     return true;
 }
});
return true;
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState)
{
super.onRestoreInstanceState(savedInstanceState);
}

Camera.PictureCallback mPictureCallbackRaw = new Camera.PictureCallback() {
public void onPictureTaken(byte[] data, Camera c) {
 Log.e(getClass().getSimpleName(), "PICTURE CALLBACK RAW: " + data);
 camera.startPreview();
}
};

Camera.PictureCallback mPictureCallbackJpeg= new Camera.PictureCallback() {
public void onPictureTaken(byte[] data, Camera c) {
 Log.e(getClass().getSimpleName(), "PICTURE CALLBACK JPEG: data.length = " + data);
}
};

Camera.ShutterCallback mShutterCallback = new Camera.ShutterCallback() {
public void onShutter() {
Log.e(getClass().getSimpleName(), "SHUTTER CALLBACK");
}
};


public boolean onKeyDown(int keyCode, KeyEvent event)
{
ImageCaptureCallback iccb = null;
if(keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
try {
String filename = timeStampFormat.format(new Date());
ContentValues values = new ContentValues();
values.put(Media.TITLE, filename);
values.put(Media.DESCRIPTION, "Image capture by camera");
Uri uri = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, values);
//String filename = timeStampFormat.format(new Date());
iccb = new ImageCaptureCallback( getContentResolver().openOutputStream(uri));
} catch(Exception ex ){
ex.printStackTrace();
Log.e(getClass().getSimpleName(), ex.getMessage(), ex);
}
}
if (keyCode == KeyEvent.KEYCODE_BACK) {
 return super.onKeyDown(keyCode, event);
}

if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
 camera.takePicture(mShutterCallback, mPictureCallbackRaw, iccb);
 return true;
}

return false;
}

protected void onResume()
{
Log.e(getClass().getSimpleName(), "onResume");
super.onResume();
}

protected void onSaveInstanceState(Bundle outState)
{
super.onSaveInstanceState(outState);
}

protected void onStop()
{
Log.e(getClass().getSimpleName(), "onStop");
super.onStop();
}

public void surfaceCreated(SurfaceHolder holder)
{
Log.e(getClass().getSimpleName(), "surfaceCreated");
camera = Camera.open();
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h)
{
Log.e(getClass().getSimpleName(), "surfaceChanged");
if (isPreviewRunning) {
 camera.stopPreview();
}
Camera.Parameters p = camera.getParameters();
p.setPreviewSize(w, h);
camera.setParameters(p);
camera.setPreviewDisplay(holder);
camera.startPreview();
isPreviewRunning = true;
}

public void surfaceDestroyed(SurfaceHolder holder)
{
Log.e(getClass().getSimpleName(), "surfaceDestroyed");
camera.stopPreview();
isPreviewRunning = false;
camera.release();
}
}

ImageCaptureCallback.java


public class ImageCaptureCallback implements PictureCallback  {

private OutputStream filoutputStream;
public ImageCaptureCallback(OutputStream filoutputStream) {
this.filoutputStream = filoutputStream;
}
@Override
public void onPictureTaken(byte[] data, Camera camera) {
try {
Log.v(getClass().getSimpleName(), "onPictureTaken=" + data + " length = " + data.length);
filoutputStream.write(data);
filoutputStream.flush();
filoutputStream.close();
} catch(Exception ex) {
ex.printStackTrace();
}
}
}

2. Create the main.xml as shown below

3. Add a camera permission to the ApplicationManifest

Source Code

Android Map Viewer

2008-10-27T01:27:00.015+08:00

1. Create MapViewer Project
- Create MapViewer class that extends MapActivity


package javapadawan.android;

import android.os.Bundle;
import android.view.KeyEvent;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;

public class MapViewer extends MapActivity {
private MapView map;
private MapController mc;
private static int zoomValue = 1;

@Override
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  map = (MapView) findViewById(R.id.map);
  mc = map.getController();
  mc.setZoom(zoomValue);
}

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
if(event.getKeyCode() == KeyEvent.KEYCODE_DPAD_UP) {
zoomValue = zoomValue + 1;
mc.setZoom(zoomValue);
} else if(event.getKeyCode() == KeyEvent.KEYCODE_DPAD_DOWN) {
zoomValue = zoomValue - 1;
mc.setZoom(zoomValue);
} else if(event.getKeyCode() == KeyEvent.KEYCODE_DPAD_LEFT) {
map.setSatellite(false);
} else if(event.getKeyCode() == KeyEvent.KEYCODE_DPAD_RIGHT) {
map.setSatellite(true);
}
return super.dispatchKeyEvent(event);
}

@Override
protected boolean isRouteDisplayed() {
return false;
}
}

2. Modify main.xml

3. Set the required permissions in the AndroidManifest.xml

4. Clean, Build and Run the Project. You will see an Empty Map Grid instead of a google map.

4. The reason why the code does not work is that the apiKey needs to be a valid key from google. Below are the steps to obtain a valid key.

- Obtaining a Maps API Key

- Edit the main.xml and replace apiKey with the value from google. See below on how to generate an MD5 Certificate fingerprint.

5. Now clean, build and compile again. Click the UP/Down to ZOOM, and LEFT/RIGHT to switch Map View and Satellite View.

6. Now that I got Map View to work, maybe I'll create something useful next time.

Source Code

Android Simple SQLiteDatabase

2008-10-19T23:35:00.004+08:00

Account List

New Account

Modify Account

Source Code can be downloaded below. Also, the syntaxhighlighter for the XML code, has some problems. For some reason, the JS and CSS I used modifies the XML I place. Just check with the code downloadable below for the correct xml files.

New Classes Used:
ListActivity
SQLiteOpenHelper

1. Create new Android Project.
-Activity Name: AccountList

2. Create View Classes and XML

2.1 Create account_list.xml

account_row.xml

2.2. Create ListActivity class AccountList


public class AccountList extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.account_list);
initComponents();
}
private void initComponents() {
}
}

2.3 Create account_detail.xml
Below is an example of combining two or more layouts.

2.4. Create Activity class AccountDetail


public class AccountDetail extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.account_detail);
initComponents();
}
private void initComponents() {
}
}

3. Create Model Classes
3.1 Create Account class


public class Account {
public static final String COL_ROW_ID = "_id";
public static final String COL_SERVER_NAME = "server_name";
public static final String COL_USERNAME = "username";
public static final String COL_PASSWORD = "password";
public static final String SQL_TABLE_NAME = "account_db";
public static final String SQL_CREATE_TABLE = "CREATE TABLE "
+ SQL_TABLE_NAME + " "
+ " (_id integer primary key autoincrement, "
+ "server_name text not null, username text not null, "
+ "password text not null); ";

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public String getServerName() {
return serverName;
}

public void setServerName(String serverName) {
this.serverName = serverName;
}

private String username;

private String password;

private String serverName;

private int id;
}

3.2 Create ActiveRecord interface
This is the interface that will be extend by POJO to make it a sort-of Active Domain. I'm not really experienced with the Active Domain pattern but this is my understanding of it. So just correct me if I am wrong and I'll change the code.


public interface ActiveRecord {
public long save();
public boolean delete();
public void load(Activity activity);
public Cursor retrieveAll();
public void setSQLiteDatabase(SQLiteDatabase sqliteDb);
}

3.3 Extend SQLiteOpenHelper
I derived MyDatabaseAdapter class from
Tutorial: A Notepad Application, However I made the MyDatabaseAdapter as a utility class instead of placing CRUD functions inside it. I made the Controller a sort-of Active Domain pattern so that the MyDatabaseAdapter can be re-used for future applications.


public class MyDatabaseAdapter extends SQLiteOpenHelper {
private static SQLiteDatabase sqliteDb;
private static MyDatabaseAdapter instance;

private static final String DATABASE_NAME = "simple_sqlite_db";
private static final int DATABASE_VERSION = 1;


private MyDatabaseAdapter(Context context, String name, CursorFactory factory, int version) {
super(context, name, factory, version);
}

@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(Account.SQL_CREATE_TABLE);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(getClass().getSimpleName(), "Upgrading database from version " + oldVersion + " to "
       + newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS " + Account.SQL_TABLE_NAME );
onCreate(db);
}

private static void initialize(Context context) {
if(instance == null) {
instance = new MyDatabaseAdapter(context, DATABASE_NAME, null, DATABASE_VERSION);
sqliteDb = instance.getWritableDatabase();
}
}

public static final MyDatabaseAdapter getInstance(Context context) {
initialize(context);
return instance;
}

public SQLiteDatabase getDatabase() {
return sqliteDb;
}

public void close() {
if(instance != null ) {
instance.close();
instance = null;
}
}
}

3.4 Create implementation of ActiveRecord on Account class
Here's the code that implements the CRUD methods of the ActiveRecord interface. I also learned that from the Notepad Tutorial, since the Android Docs, does not really explain how to use SQLiteDB, or maybe I just do not know where to look.


public class Account implements ActiveRecord {

public static final String COL_ROW_ID = "_id";
public static final String COL_SERVER_NAME = "server_name";
public static final String COL_USERNAME = "username";
public static final String COL_PASSWORD = "password";

public static final String SQL_TABLE_NAME = "account_db";
public static final String SQL_CREATE_TABLE = "CREATE TABLE "
+ SQL_TABLE_NAME + " "
+ " (_id integer primary key autoincrement, "
+ "server_name text not null, username text not null, "
+ "password text not null); ";

private SQLiteDatabase sqliteDatabase;

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public String getServerName() {
return serverName;
}

public void setServerName(String serverName) {
this.serverName = serverName;
}

private String username;

private String password;

private String serverName;

private int id;

@Override
public void load(Activity activity) {
Cursor cursor = sqliteDatabase.query(true, SQL_TABLE_NAME,
new String[] { COL_ROW_ID, COL_SERVER_NAME, COL_USERNAME,
COL_PASSWORD }, COL_ROW_ID + "=" + id, null, null,
null, null, null);
if (cursor != null) {
cursor.moveToFirst();
activity.startManagingCursor(cursor);
setId(cursor.getInt(cursor
.getColumnIndex(COL_ROW_ID)));
setPassword(cursor.getString(cursor
.getColumnIndex(COL_PASSWORD)));
setUsername(cursor.getString(cursor
.getColumnIndex(COL_USERNAME)));
setServerName(cursor.getString(cursor
.getColumnIndex(COL_SERVER_NAME)));
}
}

@Override
public Cursor retrieveAll() {
return sqliteDatabase.query(SQL_TABLE_NAME, new String[] { COL_ROW_ID,
COL_SERVER_NAME, COL_USERNAME, COL_PASSWORD }, null, null,
null, null, null);
}

@Override
public long save() {
ContentValues values = new ContentValues();
if (id <= 0) {    values.put(COL_SERVER_NAME, serverName);    values.put(COL_USERNAME, username);    values.put(COL_PASSWORD, password);    return sqliteDatabase.insert(SQL_TABLE_NAME, null, values);   } else {    values.put(COL_SERVER_NAME, serverName);    values.put(COL_USERNAME, username);    values.put(COL_PASSWORD, password);    return sqliteDatabase.update(SQL_TABLE_NAME, values, COL_ROW_ID      + "=" + id, null);   }  }   public boolean delete() {   return sqliteDatabase.delete(SQL_TABLE_NAME, COL_ROW_ID + "=" + id,     null) > 0;
}

@Override
public void setSQLiteDatabase(SQLiteDatabase sqliteDatabase) {
this.sqliteDatabase = sqliteDatabase;
}
}

4. Create Controllers
4.1 AccountList Controllers
For the AccountList I used the OptionsMenu.


public class AccountList extends ListActivity {
/** Called when the activity is first created. */
private MyDatabaseAdapter myDatabaseAdapter;

private static final int INTENT_NEXT_SCREEN = 0;
public static final String INTENT_EXTRA_SELECTED_ROW = "SELECTED_ROW";

private static final int INSERT_ID = Menu.FIRST;
private static final int DELETE_ID = Menu.FIRST + 1;
private static final int EXIT_ID = DELETE_ID + 1;
private Account account = new Account();
private Intent intent;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.account_list);
myDatabaseAdapter = MyDatabaseAdapter.getInstance(this);
intent = new Intent(this, AccountDetail.class);
initComponents();
}

private void initComponents() {
account.setSQLiteDatabase(myDatabaseAdapter.getDatabase());
Cursor recordsCursor = account.retrieveAll();
startManagingCursor(recordsCursor);
String[] from = new String[] { Account.COL_SERVER_NAME };
int[] to = new int[] { R.id.tfServerName };
SimpleCursorAdapter records = new SimpleCursorAdapter(this,
R.layout.account_row, recordsCursor, from, to);
setListAdapter(records);
}

@Override
public boolean onMenuItemSelected(int featureId, MenuItem item) {
switch (item.getItemId()) {
case INSERT_ID:
createRecord();
return true;
case DELETE_ID:
account.setId((int) getListView().getSelectedItemId());
account.delete();
initComponents();
return true;
case EXIT_ID:
finish();
}
return super.onMenuItemSelected(featureId, item);
}

private void createRecord() {
intent.putExtra(INTENT_EXTRA_SELECTED_ROW, 0);
startActivityForResult(intent, INTENT_NEXT_SCREEN);
}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
Log.v(getClass().getSimpleName(), "id=" + id);
intent.putExtra(INTENT_EXTRA_SELECTED_ROW, id);
startActivityForResult(intent, INTENT_NEXT_SCREEN);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
menu.add(0, INSERT_ID, 0, R.string.btnAdd);
menu.add(0, DELETE_ID, 0, R.string.btnDelete);
menu.add(0, EXIT_ID, 0, R.string.btnExit);
return true;
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
initComponents();
}
}

4.2 AccountDetail Controllers


public class AccountDetail extends Activity implements OnClickListener {

private MyDatabaseAdapter myDatabaseAdapter;
private long selectedRow;
private TextView tvId;
private EditText etServerName, etUserName, etPassword;
private Button btnSave, btnCancel;
private Account account;

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.account_detail);
myDatabaseAdapter = MyDatabaseAdapter.getInstance(this);
initComponents();
}

private void initComponents() {
selectedRow = getIntent().getLongExtra(
AccountList.INTENT_EXTRA_SELECTED_ROW, 0);
tvId = (TextView) findViewById(R.id.tvId);
etServerName = (EditText) findViewById(R.id.etServerName);
etUserName = (EditText) findViewById(R.id.etUsername);
etPassword = (EditText) findViewById(R.id.etPassword);

account = new Account();
account.setSQLiteDatabase(myDatabaseAdapter.getDatabase());
Log.v(getClass().getSimpleName(), "selectedRow=" + selectedRow);
account.setId((int) selectedRow);
if (selectedRow > 0) {
account.load(this);
}
Log.v(getClass().getSimpleName(), "account.getId()=" + account.getId());
if (account.getId() > 0) {
tvId.setText(account.getId() + "");
etServerName.setText(account.getServerName());
etUserName.setText(account.getUsername());
etPassword.setText(account.getPassword());
} else {
tvId.setText("new");
}
btnSave = (Button) findViewById(R.id.btnSave);
btnSave.setOnClickListener(this);
btnCancel = (Button) findViewById(R.id.btnCancel);
btnCancel.setOnClickListener(this);
}

Source Code
If you find something confusing from this tutorial, just post a comment, and I'll fix it for you.

In order to display multiple items on the list, just edit account_row.xml as shown below.


 android:layout_width="fill_parent" android:layout_height="wrap_content">
      android:layout_width="wrap_content" android:layout_alignParentRight="false"
     android:layout_height="wrap_content" android:text="Server Name" />
      android:layout_width="wrap_content"
     android:layout_height="wrap_content" android:layout_toRightOf="@id/tfServerName" 
     android:text="Username"/>

Also modify AccountList.java to display the fields you want.


String[] from = new String[] { Account.COL_SERVER_NAME, Account.COL_USERNAME};
int[] to = new int[] { R.id.tfServerName, R.id.tfUsername };

Android Networking, User Experience and Threads

2008-10-12T21:27:00.021+08:00

This tutorial is an android version of good old J2ME tutorial about Networking, User Experience and Threads; thus, I won't make my own J2ME tutorial for that.

Source code can be downloaded below.

For this Simple Http Connection application, it uses the following classes:

Handler
Intent
ProgressBar

Unlike, the hello world tutorial, where only an alert screen shows, this tutorial will have two screens or two activities. So, I'll get started.

First, create two activity classes for the first screen and the next screen.

SimpleHttpConnection.java is the MAIN activity,
NextScreen.java will display the network response.

Here's what the SimpleHttpConnection (main.xml) looks like.
The white space on top of the buttons is supposed to be the progress bar, for some reason the android eclipse plug-in does not render it properly.

 @Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
initComponents();
}

private void initComponents() {
connectIntent = new Intent(this, NextScreen.class);
progressBar = (ProgressBar) findViewById(R.id.pbProgressBar);
progressBar.setVisibility(ProgressBar.INVISIBLE);
btnConnect = (Button) findViewById(R.id.btnConnect);
btnConnect.setOnClickListener(this);
btnCancel = (Button) findViewById(R.id.btnCancel);
btnCancel.setOnClickListener(this);
btnCancel.setVisibility(Button.INVISIBLE);
}

Above is the code, for the user interface. Notice that the btnCancel and the progressBar is set to invisible. It will be visible to the user once btnConnect is clicked. Here's what the user-interface will look like.

@Override
public void onClick(View v) {
if (v == btnConnect) {
try {
networkConnection = new NetworkConnection(progressBar,
getString(R.string.simplehttpurl), this,
connectIntent, INTENT_NEXT_SCREEN);
networkConnection.start();
btnConnect.setVisibility(Button.INVISIBLE);
btnCancel.setVisibility(Button.VISIBLE);
} catch (Exception ex) {
Log.e(getClass().getName(), "Error on onClick btnConnect ", ex);
}
} else if(v == btnCancel) {
if(networkConnection != null) {
try {
networkConnection.close();
} catch(Exception ex) {
Log.e(getClass().getName(), "Error on onClick btnCancel ", ex);
}
}
reset();
}
}

When btnConnect is clicked, it initializes the NetworkConnection class and sends the request to the server. The btnConnect button is then set to invisible then the cancel button is set to visible. When the btnCancel is clicked, it will then interrupt the connection, and enables the btnConnect again, disabling the btnCancel and resets the progress bar.

The NetworkConnection class implements Runnable since it will run as another thread.


public class NetworkConnection implements Runnable

Network Connection uses the following parameters:

progressBar - passes the screen's progress bar to be update the progress.
serverUrl - the server's url.
activity - the previous activity, this will be used to call startActivityForResult(intent, intentId);
nextIntent - the next activity to be run after the network connection is done.
intentId - the requestCode used by the Main Activity's onActivityResult method show below.


protected void onActivityResult(int requestCode, int resultCode, Intent data) {
Log.v(getClass().getName(), requestCode + " - " + resultCode);
if (requestCode == INTENT_NEXT_SCREEN) {
reset();
}
}

When the NetworkConnection is started, a thread is created and the HTTP connection starts.

public void start() throws IOException {
runner = new Thread(this);
runner.start();
}

public void run() {
try {

transfer(serverUrl);
} catch (Exception e) {
Log.e(getClass().getName(), "Error on startStreaming ", e);
return;
}
}

public void transfer(String urlStr) throws IOException {
url = new URL(urlStr);
urlConnection = url.openConnection();
inputStream = urlConnection.getInputStream();
if (inputStream == null) {
Log.e(getClass().getName(), "Error on transfer " + url);
}
int contentLength = (int) urlConnection.getContentLength();
if (contentLength == -1)
contentLength = 255;
int ch = 0;
total = contentLength;
Log.v(getClass().getName(), contentLength + "");
StringBuffer buffer = new StringBuffer();
while ((ch = inputStream.read()) != -1) {
buffer.append((char) ch);
fireDataLoadUpdate();
current++;
}
inputStream.close();
response = buffer.toString();
Log.v(getClass().getName(), response);
intent.putExtra(NC_RESPONSE, response);
parent.startActivityForResult(intent, intentId);
}

private void fireDataLoadUpdate() {
Runnable updater = new Runnable() {
public void run() {
double loadProgress = ((double) current / (double) total);
Log.v(getClass().getName(), "loadProgress=" + loadProgress);
progressBar.setProgress((int) (loadProgress * 100));
progressBar.setSecondaryProgress((int) (loadProgress * 100));
Log.v(getClass().getName(), "" + progressBar.getProgress());
}
};
handler.post(updater);
}

The transfer method, is just a basic HTTP connection, its just opens a connections from the url then opens an input stream. The important part of this method is


intent.putExtra(NC_RESPONSE, response);
parent.startActivityForResult(intent, intentId);

This code, puts the server response in the intent.putExra, then starts the next activity, which was defined on the first screen.

Also, the NetworkConnection has close method, that when the user clicks, it cancels the operation. The method I created is a crude one without any graceful handling. But for this app, it does not need to. If you're app parses data and saves them somewhere, be careful in using this since it will corrupt your data.


public void close() {
if (runner != null) {

if(inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
}
inputStream = null;
}
if(urlConnection != null) {
try {
urlConnection = null;
} catch(Exception ex) {
}
}
try {
runner.interrupt();
runner.join();
runner = null;
} catch (InterruptedException e) {
//Thread.currentThread().interrupt();
}
}
}

NextScreen.java

public class NextScreen extends Activity implements OnClickListener {
private Button btnBack;
private TextView tvMessage;
private String message;

@Override
public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.nextscreen);
initComponents();
}

public void initComponents() {
message = getIntent().getStringExtra(NetworkConnection.NC_RESPONSE);
tvMessage = (TextView) findViewById(R.id.tvMessage);
if (message != null) {
tvMessage.setText(message);
} else {
tvMessage.setText("Message is null");
}
btnBack = (Button) findViewById(R.id.btnBack);
btnBack.setOnClickListener(this);
}

@Override
public void onClick(View v) {
if (v == btnBack) {
finish();
}
}
}

On the initComponent method, the Intent Extra is that was set in the NetworkConnection class was retrieved then set on the TextView.

Here's what it looks like.

When the Back button is clicked, the finish() method is called, signifying that the Activity is done. Thus, it goes back to the main screen, and calling the onActivityResult method. For this, application, I just reset the progress bar, and the buttons.

Also, do not forget to add permission, or you might get a Socket Exception.

Modify the Android Manifest and add
uses-permission name="android.permission.INTERNET"

See the AndroidManifest.xml in the source code for more details.

Source Code

Java Source Code Style

2008-10-12T14:05:00.008+08:00

I just found out how to write Java and XML code with syntax highlights in blogger.
You can find the project here. So on the next post, i'll use it instead of screen captures of the source code.

public class HelloWorld {
private String message = "Hello World";

public static void main(String[] args) {
System.out.println(message);
}
}

Hello World Android version

2008-09-28T16:12:00.020+08:00

For J2ME developers, read the J2ME version first.

Link for the source code at the end of the tutorial.

Step 1. Create Android Project By File > New then select Android Project.

Step 2. Enter Project Name, to be consistent with the J2ME version, I chose HelloWorld.

Android enforces a two identifier package, thus javapadawan.android is used.
The Activity name, entered in above will serve as the entry point of the application. This is similar to J2ME's MIDlet. One can create multiple MIDlets, but only once can be used as a program entry point.

Step 3. Create HelloWorldActivity.java.

Note that R.java is generated by the Eclipse Android plug-in, so don't bother with that. Also, when encountering compile problems with R.java, just do a Clean on the Eclipse Menu Project>Clean then Build the Project.

Step 4. Creating the User Interface.

When you created the HelloWorldActivity, the Eclipse Android plug-in already created the layout XML.

Above is generated XML. Although, one can program Android user-interfaces by hand, without using XML, but that's considered an advanced topic. Similar to coding UIs using MIDP's Canvas.

Below is the User Interface similar to the J2ME version of the HelloWorld. The one's encircled in red are going to be used in the HelloWorldActivity class, the @+id/ should be unique. The usage of such will be shown below. Further, detailed explaination for the xml layouts will come in the future tutorials.

Above is the result of the xml layout above. This uses the RelativeLayout.

Step 5. Coding the HelloWorldActivity.

As much as possible, I want the Android version to be similar to the J2ME version of the HelloWorld so that a J2ME developer may see the differences.

Thus, I also included a initComponents() method. This is where the User Interface Components defined in the XML are retrieved.

Notice the usage of the R.java. Whenever, there are thing modified in the XMLs such as the main.xml and string.xml, it gets reflected here.

The android:id identified above will become R.id..

So to be able to use the User Interface components, it need to be retrieved using the Activity method, findByViewId(...). The parameter needed by findByViewId is integer, but the R.java values should be used.

So just set the values of the findById(...) to a private variable inside the class. For the buttons, (similar to MIDP), listeners must be assigned. Since I used the same class as the listener in J2ME, I will also use the same for Android.

So just, add implements OnClickListener to the class and implement its method.

Similar to J2ME's commandAction(Command c, Displayable d), when a button is clicked, the View (Component) responsible to the event is also passed in the onClick(View v) method.

So above is the implementation I did. Notice the similarities of the MIDP version.

However, the Alert is quite different and more complex in android. Just see the AlertBuilder API.

Step 6. Clean, Build and Run

Clean and Buld the Project.

Run by going to the Menu then Run > Run (Ctrl + F11).
Then Run As Android Applicaiton. On the first Run, this may take a couple of minutes depending on your Hardware.

Step 7. Debugging and Cleaning the Emulator.
Unlike in Netbeans IDE, Mobility where the System.out.print, and stacktraces displays on the IDE's consolde

In Eclipse Android Plug-in, you need to go to the DDMS perspective to debug. Open a new Perspective Window > Open Perspective > Other

On the dialog, select DDMS.

Here's what the DDMS Perspective looks like. Also, you may delete the installed apps if you want. Highlight the .apk to be deleted and click the red (-) minus button shown.

Source Code

Hello World J2ME version

2008-09-28T15:26:00.037+08:00

Before reading this, you should have downloaded Netbeans IDE 6.1, choose the Mobility version or the All version.

When creating a J2ME application, I usually separate my MIDlet class, view-controller classes and model classes.

I do not separate View and Controller since normally my views only have a couple of controls and I find it more organized that way.

Link for the source code at the end of the tutorial.

Step 1. Create a new Project By File>New Project
Click Mobility from the Categories and MIDP Application from Projects.

Step 2. Write any Project Name and select a project location then click the Next Button.
Step 3. Select CLDC 2.0 and MIDP 2.0

Step 4. Click Finish. Delete all generated .java files as we will not be using the WYSIWYG editor.

Then create two classes, HelloWorldForm.java and HelloWorldMIDlet.java
You should have the following files on your Project Tab.

Step5. Writing the HelloWorldMIDlet.java code.

PauseApp, destroyApp and startApp are the abstract classes of the MIDlet class that needs to be implemented. I added two methods to be used by the UI class, showScreen(Displayble d) and showScreenAndAlert(Alert a, Displayble d).

The code in startApp() will be discussed after the next step.

Step 6. Coding the HelloWorldForm.java.

As you may have noticed, the MIDlet class is passed to the constructor, I find this useful in creating a apps with a lot of forms. Further, the MIDlet class may also be used to store Application sessions data, also handling unexpected application problems.

The initComponents() method is where the UI Components are initialized and added to the Form.

If you do not want the controller and the view to be on the same class, you may create, or pass in the constructor a class that implements the CommandListener interface.

On the code, instead of setCommandListener(this), just replace this with a CommandListener instance.

Step 7. Building and Running.

Source Code

About.

2008-09-28T12:17:00.002+08:00

I am a Java Mobile Edition developer ever since MIDP 1.0, I've already experienced and done the workarounds of almost all of the limitation of the MIDP platform. The worst ever is not being able to get the Mobile Number of the Phones (This is for most Phones, some implementations offer a native utility for retrieving IMEI, Numbers, Contacts but not the standard MIDP API).

When I first reviewed Google Android, I got excited with the fact that everything in the phones is programmable and is not limited to a J2ME like tiny little sandbox. I worry about the Device's security though.

I'll be starting a Journal of how to program Android from a J2ME Developer's Perspective. I am planning to use my knowledge in MIDP, and try to figure out how to port it in android. In the future, I may start on some advanced Android apps and see what the android can really do.