How to get and set JSONObject, JSONArray in J2ME

Question

I am new to JSON programming in J2ME.

I found that Json is used to exchange data like XML.

I want to know about sharing in an Array from JSONtoObject and vice versa

Below is the code in which I convert from JSON to Object and vice versa.

But I do not know how to do this for a complex data structure, such as arrays, etc.

// App Loader

import javax.microedition.midlet.MIDlet; import javax.microedition.midlet.MIDletStateChangeException; public class AppLoader extends MIDlet { public AppLoader() { // TODO Auto-generated constructor stub // Converting Object to JSON UserData data=new UserData(); data.setId(10); data.setName("Yatin"); data.setDescription("Testing JSON in J2ME"); System.out.println("Convert to JSON"+data.toJSON()); //Convert JSON to Object String sample="{\"id\":99,\"name\":\"Tester\",\"description\":\"This is JSON Data\"}"; UserData data2=new UserData(); data2.fromJSON(sample); System.out.println("Convert from JSON "+data2); } protected void destroyApp(boolean arg0) throws MIDletStateChangeException { // TODO Auto-generated method stub } protected void pauseApp() { // TODO Auto-generated method stub } protected void startApp() throws MIDletStateChangeException { // TODO Auto-generated method stub } } 

In this class, I created getters and setters for the String type, and then created a JsonObject to create a JSON object to create a JSON object, and then vice versa according to toJSON() and fromJSON() functions

// user data class

 import org.json.me.JSONException; import org.json.me.JSONObject; public class UserData { private int id; private String name; private String description; 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 getDescription() { return description; } public void setDescription(String description) { this.description = description; } public String toString() { return getId()+"-"+getName()+"-"+getDescription(); } public String toJSON() { // TODO Auto-generated method stub JSONObject inner=new JSONObject(); try { inner.put("id",getId()); inner.put("description", getDescription()); inner.put("name", getName()); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } return inner.toString(); } public void fromJSON(String jsonString) { // TODO Auto-generated method stub try { JSONObject json=new JSONObject(jsonString); setId(json.getInt("id")); setDescription(json.getString("description")); setName(json.getString("name")); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } 

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I found a better link for this question

http://jimmod.com/blog/2011/09/java-me-j2me-json-implementation-for-array-object/

Answer 1

Check this link for another sample JSON dataset

One example for your understanding: JSON String with arrays

 { "id": "0001", "type": "donut", "name": "Cake", "ppu": 0.55, "batters": { "batter": [ { "id": "1001", "type": "Regular" }, { "id": "1002", "type": "Chocolate" }, { "id": "1003", "type": "Blueberry" }, { "id": "1004", "type": "Devil Food" } ] }, "topping": [ { "id": "5001", "type": "None" }, { "id": "5002", "type": "Glazed" }, { "id": "5005", "type": "Sugar" }, { "id": "5007", "type": "Powdered Sugar" }, { "id": "5006", "type": "Chocolate with Sprinkles" }, { "id": "5003", "type": "Chocolate" }, { "id": "5004", "type": "Maple" } ] } 

To check whether it is correct or not check this link (JSON Validator)

To check JSON Viewer

So, look at the code:

 String json = "{\"id\":\"0001\",\"type\":\"donut\",\"name\":\"Cake\"" + ",\"ppu\":0.55,\"batters\":{\"batter\":[" + "{\"id\":\"1001\",\"type\":\"Regular\"},{\"id\":\"1002\"," + "\"type\":\"Chocolate\"},{\"id\":\"1003\"," + "\"type\": \"Blueberry\" },{ \"id\": \"1004\", " + "\"type\": \"Devil Food\" } ] }," + " \"topping\":[" + "{ \"id\": \"5001\", \"type\": \"None\" }," + "{ \"id\": \"5002\", \"type\": \"Glazed\" }," + "{ \"id\": \"5005\", \"type\": \"Sugar\" }," + "{ \"id\": \"5007\", \"type\": \"Powdered Sugar\" }," + " { \"id\": \"5006\", \"type\": \"Chocolate with Sprinkles\" }," + "{ \"id\": \"5003\", \"type\": \"Chocolate\" }," + "{ \"id\": \"5004\", \"type\": \"Maple\" }]}"; try { JSONObject root = new JSONObject(json); String id = root.getString("id"); double dd = root.getDouble("ppu"); System.out.println(""+id); System.out.println(""+dd); JSONObject batters=new JSONObject(root.getString("batters")); JSONArray batter=new JSONArray(batters.getString("batter")); for(int j=0;j<batter.length();j++){ JSONObject navgt_batter=new JSONObject(batter.getString(j)); String id_batter= navgt_batter.getString("id"); String type_batter=navgt_batter.getString("type"); System.out.println(""+id+" "+type_batter); } JSONArray topping=root.getJSONArray("topping"); for(int k=0;k<topping.length();k++){ JSONObject navgt_batter=new JSONObject(topping.getString(k)); String id_top =navgt_batter.getString("id"); String type_top=navgt_batter.getString("type"); System.out.println(""+id_top+" "+type_top); } } catch (JSONException ex) { ex.printStackTrace(); } 

You can use your concept to set up and retrieve data similar to the above. complex data structure is always easily processed in JSON, do not worry about it. Thanks

Answer 2

In the link below http://jimmod.com/blog/2011/09/java-me-j2me-json-implementation-for-array-object/

they explained how JSONArray is used

 public void fromJSON(String jsonString) { try { JSONObject json = new JSONObject(jsonString); setApi_status(json.getString("api_status")); JSONArray jsonArray = json.getJSONArray("threads"); int total = jsonArray.length(); ThreadData[] threads = new ThreadData[total]; for (int i=0;i<total;i++) { String threadsJSON = jsonArray.getString(i); threads[i] = new ThreadData(); threads[i].fromJSON(threadsJSON); } setThreads(threads); } catch (JSONException ex) { ex.printStackTrace(); } } public String toJSON() { JSONObject inner = new JSONObject(); try { inner.put("api_status", getApi_status()); JSONArray jsonArray = new JSONArray(); ThreadData[] threads = getThreads(); for (int i=0;i<threads.length;i++) { jsonArray.put(threads[i].toJSON()); } inner.put("threads", jsonArray); } catch (JSONException ex) { ex.printStackTrace(); } return inner.toString(); } 

Where Threaddata is the class defined for JSONObject and it was created in an array object check the link

Answer 3

It's not like that at all. All you need to do is just skip the array ... I have added tags to your sample JSON data.

  String sample = "{\"id\":99,\"name\":\"Tester\",\"description\":\"This is JSON Data\",\"tags\":[\"eat\",\"swim\",\"sleep\"]}"; try { JSONObject objSample = new JSONObject(sample); JSONArray array = new JSONArray(objSample.getJSONArray("tags").toString()); System.out.println(objSample.get("id").toString()); System.out.println(objSample.get("name").toString()); System.out.println(objSample.get("description").toString()); for (int i = 0; i < array.length(); i++) { System.out.println(array.get(i).toString()); } } catch (Exception e) { System.out.println(e.getMessage()); } } 

Output

  99 Tester This is JSON Data eat swim sleep 

I hope this helps

Thanks :)