Twitter is a great source for JSON. You can just call a URI and retrieve JSON. Here are some examples:

Please note that some URIs return a JSONObject object while others return a JSONArray.

Create a new Android project “de.vogella.android.twitter.json” with the package “de.vogella.android.twitter.json” and the activity “ParseJSON”.

Create the following coding for the activity. This will download the twitter feed for the user http://twitter.com/vogella and write the number of entries and the text messages to the Android log file.

package de.vogella.android.twitter.json;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class ParseJSON extends Activity {

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		String readTwitterFeed = readTwitterFeed();
		try {
			JSONArray jsonArray = new JSONArray(readTwitterFeed);
			Log.i(ParseJSON.class.getName(),
					"Number of entries " + jsonArray.length());
			for (int i = 0; i < jsonArray.length(); i++) {
				JSONObject jsonObject = jsonArray.getJSONObject(i);
				Log.i(ParseJSON.class.getName(), jsonObject.getString("text"));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public String readTwitterFeed() {
		StringBuilder builder = new StringBuilder();
		HttpClient client = new DefaultHttpClient();
		HttpGet httpGet = new HttpGet("http://twitter.com/statuses/user_timeline/vogella.json");
		try {
			HttpResponse response = client.execute(httpGet);
			StatusLine statusLine = response.getStatusLine();
			int statusCode = statusLine.getStatusCode();
			if (statusCode == 200) {
				HttpEntity entity = response.getEntity();
				InputStream content = entity.getContent();
				BufferedReader reader = new BufferedReader(new InputStreamReader(content));
				String line;
				while ((line = reader.readLine()) != null) {
					builder.append(line);
				}
			} else {
				Log.e(ParseJSON.class.toString(), "Failed to download file");
			}
		} catch (ClientProtocolException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return builder.toString();
	}
}

To run this example assign the uses-permission to your AndroidManifest.xml for “android.permission.INTERNET”.

Writing JSON is very simple. Just create the JSONObject or JSONArray and use the toString() method.

				
public void writeJSON() {
	JSONObject object = new JSONObject();
	try {
		object.put("name", "Jack Hack");
		object.put("score", new Integer(200));
		object.put("current", new Double(152.32));
		object.put("nickname", "Hacker");
	} catch (JSONException e) {
		e.printStackTrace();
	}
	System.out.println(object);
}