Android Parsing JSON

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

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;
 }
}