Develop Reference

How to deal with a large JSON object on Android

I'm making an Android app that runs a ASP.NET WebService. Webservice sends a JSON object and app parses the object and displays on the screen. In one case, JSON object is too big and I get Failed Binder Transaction error. My solution is to get that JSON object and embed it in the app code, so that it wouldn't need to get that JSON object from the server. Can you tell any other things that I can do for this problem?
Or can you tell me how to get that JSON object from Webservice? Thanks.

Sending the large size data from server to mobile. JSON is light weight.
If you want to pass the data using more efficient way then passes it in pagination.
If you want to use more lighter protocol than JSON then implement the below google protocol which are really useful, which are supporting major languages.
Below are smaller Serialised data structure. Google's data interchange protocol.
1.Google Protocol
2.Flat Buffers
3.Nano-proto buffers
Hope this will be useful you.

If data is large then try to save it in the database, then deal with it using SQLite. (but not recommended if its dynamic)
To parse json object use gson or jackson. This will help reduce the memory consumption significantly as the json data being parsed partially.
get Gson, jackson here
https://sites.google.com/site/gson/gson-user-guide
http://jackson.codehaus.org/
A jackson example
http://www.mkyong.com/java/jackson-streaming-api-to-read-and-write-json/

First thing: If there is a crash or exception in your code, you'll probably want to post that. "Failed Binder Exception" is a bit too vague to understand what you're doing.
If you really want to ship your Android app with JSON embeddd inside it (to avoid having to fetch it from a server, consider storing it as an asset and access it using AssetManager. You basically drop the file with the json in your app's assets folder and read them out with AssetManager.
If you still want to download it from the server and act on it, consider using streaming APIs to download and parse the JSON. Android's JSONObject does not do this and it insists on having the entire JSON string in memory before it can be parsed.
If you want to stream directly from a URL download into a streaming parser (such as GSON), try something along these lines. First get an InputStream from the URL you're trying to fetch:
URL u = new URL(url);
URLConnection conn = u.openConnection();
InputStream is = new BufferedInputStream(conn.getInputStream());
Then feed that InputStream directly to your streaming parser. This should prevent the need to pull the entire response into memory before parsing, but you'll still need enough memory to contain all the objects that the parser creates:
GsonBuilder gb = new GsonBuilder(); // configure this as necessary
Gson gson = gb.create();
final Result response = gson.fromJson(
new InputStreamReader(is, Charset.forName("UTF-8")),
Result.class
);
"Result" here is a class that will contain the data from the JSON response. You'll have to make sure all the mappings work for your data, so read up on GSON and do whatever works for your case.
You can also use GSON to parse the JSON data if you store it in an asset. Just hand it the InputStream of the asset data and it works the same way.

The following class ApiUrlClass.java has all methods you require. Please read the comments of the class which I wrote. That will help you to do what you require. This also utilises transparent.
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Build;
import android.util.Log;
import org.apache.http.entity.mime.HttpMultipartMode;
import org.apache.http.entity.mime.content.ByteArrayBody;
import org.apache.http.entity.mime.content.ContentBody;
import org.apache.http.entity.mime.content.StringBody;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.net.UnknownHostException;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLPeerUnverifiedException;
/*
Usage of the class
Create all the necessary API Call methods you need.
And either use a Thread or AsyncTask to call the following.
JSONObject response = ApiUrlCalls.login("username", "passowrd");
After the response is obtained, check for status code like
if(response.getInt("status_code") == 200){
//TODO: code something
} else {
//TODO: code something
}
*/
public class ApiUrlCalls {
private String HOST = "https://domain/path/"; //This will be concated with the function needed. Ref:1
/*
Now utilizing the method is so simple. Lets consider a login function, which sends username and password.
See below for example.
*/
public static JSONObject login(String username, String password){
String functionCall = "login";
Uri.Builder builder = new Uri.Builder()
.appendQueryParameter("username", username)
.appendQueryParameter("password", password);
/*
The return calls the apiPost method for processing.
Make sure this should't happen in the UI thread, orelse, NetworkOnMainThread exception will be thrown.
*/
return apiPost(builder, functionCall);
}
/*
This method is the one which performs POST operation. If you need GET, just change it
in like Connection.setRequestMethod("GET")
*/
private static JSONObject apiPost(Uri.Builder builder, String function){
try {
int TIMEOUT = 15000;
JSONObject jsonObject = new JSONObject();
try {
URL url = null;
String response = "";
/*
Ref:1
As mentioned, here below, in case the function is "login",
url looks like https://domain/path/login
This is generally a rewrited form by .htaccess in server.
If you need knowledge on RESTful API in PHP, refer
http://stackoverflow.com/questions/34997738/creating-restful-api-what-kind-of-headers-should-be-put-out-before-the-response/35000332#35000332
I have answered how to create a RESTful API. It matches the above URL format, it also includes the .htaccess
*/
url = new URL(HOST + function);
HttpsURLConnection conn = null;
conn = (HttpsURLConnection) url.openConnection();
assert conn != null;
conn.setReadTimeout(TIMEOUT);
conn.setConnectTimeout(TIMEOUT);
conn.setRequestMethod("POST");
conn.setDoInput(true);
conn.setDoOutput(true);
String query = builder.build().getEncodedQuery();
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
writer.write(query);
writer.flush();
writer.close();
os.close();
conn.connect();
int responseCode = conn.getResponseCode();
String responseMessage = conn.getResponseMessage();
jsonObject.put("status_code", responseCode);
jsonObject.put("status_message", responseMessage);
/*The if condition below will check if status code is greater than 400 and sets error status
even before trying to read content, because HttpUrlConnection classes will throw exceptions
for status codes 4xx and 5xx. You cannot read content for status codes 4xx and 5xx in HttpUrlConnection
classes.
*/
if (jsonObject.getInt("status_code") >= 400) {
jsonObject.put("status", "Error");
jsonObject.put("msg", "Something is not good. Try again later.");
return jsonObject;
}
String line;
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = br.readLine()) != null) {
response += line;
}
//Log.d("RESP", response);
/*
After the actual payload is read as a string, it is time to change it into JSON.
Simply when it starts with "[" it should be a JSON array and when it starts with "{"
it is a JSONObject. That is what hapenning below.
*/
if(response.startsWith("[")) {
jsonObject.put("content", new JSONArray(response));
}
if(response.startsWith("{")){
jsonObject.put("content", new JSONObject(response));
}
} catch(UnknownHostException e) {
//No explanation needed :)
jsonObject.put("status", "UnknownHostException");
jsonObject.put("msg", "Check your internet connection");
} catch (SocketTimeoutException){
//This is when the connection timeouts. Timeouts can be modified by TIMEOUT variable above.
jsonObject.put("status", "Timeout");
jsonObject.put("msg", "Check your internet connection");
} catch (SSLPeerUnverifiedException se) {
//When an untrusted SSL Certificate is received, this happens. (Only for https.)
jsonObject.put("status", "SSLException");
jsonObject.put("msg", "Unable to establish secure connection.");
se.printStackTrace();
} catch (IOException e) {
//This generally happens when there is a trouble in connection
jsonObject.put("status", "IOException");
jsonObject.put("msg", "Check your internet connection");
e.printStackTrace();
} catch(FileNotFoundException e){
//There is no chance that this catch block will execute as we already checked for 4xx errors
jsonObject.put("status", "FileNotFoundException");
jsonObject.put("msg", "Some 4xx Error");
e.printStackTrace();
} catch (JSONException e){
//This happens when there is a troble reading the content, or some notice or warnings in content,
//which generally happens while we modify the server side files. Read the "msg", and it is clear now :)
jsonObject.put("status", "JSONException");
jsonObject.put("msg", "We are experiencing a glitch, try back in sometime.");
e.printStackTrace();
} return jsonObject;
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}

You could embed your JSON in your app's code as you suggested, but this will be a bad approach if the JSON is dynamic. Then you would need to push an update for your app whenever the JSON changes.
A better solution would be to paginate the JSON that you generate from your WebService, i.e., break the JSON into smaller parts that you can fetch sequentially in separate API calls.

Preferably try to break the Json Object to smaller object and get from webService ,
or get data in parts and if u cant do that
You have to use a streaming JSON parser.
For Android u can use these 2:
GSON
Jackson
GSON Streaming is explained at: https://sites.google.com/site/gson/streaming
I personally like Gson .

How to get restaurant menus from Locu API

I have looked at several APIs for acquiring restaurant menu for a particular location and determined that Locu API works best for me.
I was trying the basic example listed on locu website:
curl -X POST https://api.locu.com/v2/venue/search/ -d '{"fields":["name","menu_items","location","categories","description"],"menu_item_queries":[{"price":{"$lt":6},"name":"burrito"}],"venue_queries":[{"location":{"locality":"San Francisco"}}],"api_key":"MY_API_KEY"}'
Where, MY_API_KEY is the API_KEY that I received when I signed up.
As long as I include "menu_items" parameter, I keep getting the response:
{"status": "error", "http_status": 400, "error": "The requested \"menu_items\" field is either invalid or your account does not have permissions to access it."}
I did not come across any documentation regarding what I need to do in order to get the permissions for querying "menu_items". If anyone could point me in the right direction, I will really appreciate that.
I have already gone through some relatively old questions on here and they did not address this particular issue.
Also, there doesn't seem to be a tag for Locu api here. I am going to try and tag the question with some generic tags. Please excuse me for that.

I know this is an old question, but I've found that the solution is to request the "menus" field in a venue search. The API will return the "menu_items" as sub-objects of the menus.

`
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class NetClientGet {
public static void main(String[] args) {
try{
String result;
URL url = new URL("https://api.locu.com/v1_0/venue/search/?api_key=" +apiKey);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());
}
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output);}
}
conn.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}`

Error with using HttpPost on Android

I am trying to input text from Android into websites, and I read that httppost is a good option. I download the HttpClient 4.2.2 (GA) tar.gz, unzipped them, and copied the 7 jars into the lib folder of my android project in Eclipse. I'm pretty sure I got all the jars, since they matched those listed on the website.
I then proceeded to copy and paste the top tutorial from: http://hc.apache.org/httpcomponents-client-ga/quickstart.html
I imported everything, and was left with this error:
EntityUtils.consume(entity1); //X
} finally {
httpGet.releaseConnection(); //X
This portion of code is at two places in the tutorial, and errors occur at both.
Eclipse says for the first line:
"The method consume(HttpEntity) is undefined for the type EntityUtils."
Second line:
"The method releaseConnection() is undefined for the type HttpGet."
I'm pretty sure I downloaded every jar, transported them correctly, and imported everything. What is making the error? Thanks.
Here is what I have now. Edward, I used some of the code from your methods, but just put them into onCreate. However, this isn't working. A few seconds after I go from the previous activity to this one, I get the message that the app "has stopped unexpectedly".
I have a question about inputting my Strings into the website text fields: Do I use NameValuePairs of HttpParams? Here's my code, can you see what's wrong? Thanks.
package com.example.myapp;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.params.HttpClientParams;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.widget.Toast;
public class BalanceCheckerActivity extends Activity {
private final String LOGIN_URL = "https://someloginsite.com"; //username and password
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_balance_checker);
String username = getIntent().getExtras().getString("username");
String password = getIntent().getExtras().getString("password");
//Building post parameters, key and value pair
List<NameValuePair> accountInfo = new ArrayList<NameValuePair>(2);
accountInfo.add(new BasicNameValuePair("inputEnterpriseId", username));
accountInfo.add(new BasicNameValuePair("password", password));
//Creating HTTP client
HttpClient httpClient = new DefaultHttpClient();
//Creating HTTP Post
HttpPost httpPost = new HttpPost(LOGIN_URL);
BasicHttpParams params = new BasicHttpParams();
params.setParameter("inputEnterpriseID", username);
params.setParameter("password", password);
httpPost.setParams(params);
//Url Encoding the POST parameters
try {
httpPost.setEntity(new UrlEncodedFormEntity(accountInfo));
}
catch (UnsupportedEncodingException e) {
// writing error to Log
e.printStackTrace();
startActivity(new Intent(this, AccountInputActivity.class));
}
HttpResponse response = null;
InputStreamReader iSR = null;
String source = null;
// Making HTTP Request
try {
response = httpClient.execute(httpPost);
// writing response to log
Log.d("Http Response:", response.toString());
iSR = new InputStreamReader(response.getEntity().getContent());
BufferedReader br = new BufferedReader(iSR);
source = "";
while((source = br.readLine()) != null)
{
source += br.readLine();
}
} catch (ClientProtocolException e) {
// writing exception to log
e.printStackTrace();
startActivity(new Intent(this, AccountInputActivity.class));
} catch (IOException e) {
// writing exception to log
e.printStackTrace();
startActivity(new Intent(this, AccountInputActivity.class));
}
System.out.println(source);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_balance_checker, menu);
return true;
}
}

That mostly looks pretty good to me. I only saw one obviously wrong piece of code in it:
while((source = br.readLine()) != null)
{
source += br.readLine();
}
That's kind of a mess, and rather than try to untangle it, I'll just rewrite it.
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null)
sb.append(line);
String source = sb.toString();
Also, you shouldn't be doing network I/O from onCreate() or even from within your UI thread, since it can block for a long time, freezing your entire UI and possibly causing an "Application Not Responding" (ANR) crash. But for a simple test program, you can let that slide for now. For production code, you'd launch a thread or use AsyncTask().
Anyway, we're not really interested in building and debugging your program for you. Have you tried this code out? What was the result?
One final note: a login sequence like this is likely to return an authentication token in the form of a cookie. I forget how you extract cookies from an HttpResponse, but you'll want to do that, and then include any received cookies as part of any subsequent requests to that web site.
Original answer:
I think you've gotten yourself all tangled up. The Apache http client package is built into Android, so there's no need to download any jar files from apache.
I'm not familiar with EntityUtils, but whatever it is, if you can avoid using it, I would do so. Try to stick with the bundled API whenever possible; every third-party or utility library you add to your application increases bloat, and on mobile devices, you want to keep your application as light as possible. As for the actual "consume()" method not being found, that's probably a mistake in the documentation. They probably meant consumeContent().
The releaseConnection() call is probably only necessary for persistent connection. That's relatively advanced usage; I don't even do persistent or managed connections in my own code.
You haven't provided enough information to let us know what it is you're trying to do, but I'll try give you a reasonably generic answer.
There are many, many ways to transmit data to a server over the http protocol, but in the vast majority of cases you want to transmit form-encoded data via HttpPost.
The procedure is:
Create a DefaultHttpClient
Create an HttpPost request
Add headers as needed with setHeader() or addHeader().
Add the data to be transmitted in the form of an HttpEntity
Call client.execute() with the post request
Wait for and receive an HttpResponse; examine it for status code.
If you're expecting data back from the server, use response.getEntity()
There are many HttpEntity classes, which collect their data and transmit it to the server each in their own way. Assuming you're transmitting form-encoded data, then UrlEncodedFormEntity is the one you want. This entity takes a list of NameValuePair objects which it formats properly for form-encoded data and transmits it.
Here is some code I've written to do this; these are only code fragments so I'll leave it to you to incorporate them into your application and debug them yourself.
/**
* POST the given url, providing the given list of NameValuePairs
* #param url destination url
* #param data data, as a list of name/value pairs
*/
public HttpResponse post(String url, List<NameValuePair> data) {
HttpPost req = new HttpPost(url);
UrlEncodedFormEntity e;
try {
e = new UrlEncodedFormEntity(data, "UTF-8");
} catch (UnsupportedEncodingException e1) {
Log.e(TAG, "Unknown exception: " + e1);
return null; // Or throw an exception, it's up to you
}
return post(req, e);
}
/**
* Post an arbitrary entity.
* #param req HttpPost
* #param data Any HttpEntity subclass
* #return HttpResponse from server
*/
public HttpResponse post(HttpPost req, HttpEntity data) {
try {
HttpClient client = new DefaultHttpClient();
req.setEntity(data);
HttpResponse resp = client.execute(req);
int status = resp.getStatusLine().getStatusCode();
if (status != HttpStatus.SC_OK) {
Log.w(TAG,
"http error: " + resp.getStatusLine().getReasonPhrase());
return null; // Or throw an exception, it's up to you
}
return resp;
} catch (ClientProtocolException e) {
Log.e(TAG, "Protocol exception: " + e);
return null;
} catch (UnknownHostException e) {
return null;
} catch (IOException e) {
Log.e(TAG, "IO exception: " + e);
return null;
} catch (Exception e) {
// Catch-all
Log.e(TAG, "Unknown exception: " + e);
return null;
}
}

Get content of HTTPS GET request in Android

I have the following code which takes a normal HTTP GET Request and returns the output html as a string.
public static String getURLContent(String URL){
String Result = "";
String IP = "http://localhost/";
try {
// Create a URL for the desired page
URL url = new URL(IP.concat(URL));
// Read all the text returned by the server
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
String str;
while ((str = in.readLine()) != null) {
// str is one line of text; readLine() strips the newline character(s)
Result = Result+str+"~";
}
in.close();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return Result;
}
I would like to implement the same sort of thing for an unsigned ssl certificate but I am a bit of a novice at Java or Android programming and find some previous responses to similar questions very confusing.
Could someone change the code above to work with HTTPS requests?
One other question, would there be a risk of a middle-man-attack if I sent unencrypyted data via the GET request and print out database entries onto the webpage that the function returns the content of. Would it be better to use a POST request?
The reason I chose to use SSL is because someone told me that the data sent is encrypted. The data is sensitive and if I send something like localhost/login.php?user=jim&password=sd7vbsksd8 which would return "user=jim permission=admin age=23" which is data that I don't want others to see if they simply used a browser and sent the same request.

Try this:
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
public class TestHttpGet {
public void executeHttpGet() throws Exception {
BufferedReader in = null;
try {
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI("http://w3mentor.com/"));
HttpResponse response = client.execute(request);
in = new BufferedReader
(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
String page = sb.toString();
System.out.println(page);
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
We can add parameters to an HTTP Get request as
HttpGet method = new HttpGet("http://w3mentor.com/download.aspx?key=valueGoesHere");
client.execute(method);
Android should automatically work with ssl. Maybe ssl certificate you are using on localhost is not trusted? Check this: Trusting all certificates using HttpClient over HTTPS
Check if you are able to browse https://yourhost/login.php?user=jim&password=sd7vbsksd8 using your browser.

Sending and Parsing JSON Objects in Android [closed]

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I would like to send messages in the form of JSON objects to a server and parse the JSON response from the server.
Example of JSON object
{
"post": {
"username": "John Doe",
"message": "test message",
"image": "image url",
"time": "current time"
}
}
I am trying to parse the JSON manually by going attribute by attribute. Is there any library/utility I can use to make this process easier?

I am surprised these have not been mentioned: but instead of using bare-bones rather manual process with json.org's little package, GSon and Jackson are much more convenient to use. So:
GSON
Jackson
So you can actually bind to your own POJOs, not some half-assed tree nodes or Lists and Maps.
(and at least Jackson allows binding to such things too (perhaps GSON as well, not sure), JsonNode, Map, List, if you really want these instead of 'real' objects)
EDIT 19-MAR-2014:
Another new contender is Jackson jr library: it uses same fast Streaming parser/generator as Jackson (jackson-core), but data-binding part is tiny (50kB). Functionality is more limited (no annotations, just regular Java Beans), but performance-wise should be fast, and initialization (first-call) overhead very low as well.
So it just might be good choice, especially for smaller apps.

You can use org.json.JSONObject and org.json.JSONTokener. you don't need any external libraries since these classes come with Android SDK

GSON is easiest to use and the way to go if the data have a definite structure.
Download gson.
Add it to the referenced libraries.
package com.tut.JSON;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
public class SimpleJson extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
String jString = "{\"username\": \"tom\", \"message\": \"roger that\"} ";
GsonBuilder gsonb = new GsonBuilder();
Gson gson = gsonb.create();
Post pst;
try {
pst = gson.fromJson(jString, Post.class);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
Code for Post class
package com.tut.JSON;
public class Post {
String message;
String time;
String username;
Bitmap icon;
}

This is the JsonParser class
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
Note: DefaultHttpClient is no longer supported by sdk 23, so it is advisable to use target sdk 21 with this code.

There's not really anything to JSON. Curly brackets are for "objects" (associative arrays) and square brackets are for arrays without keys (numerically indexed). As far as working with it in Android, there are ready made classes for that included in the sdk (no download required).
Check out these classes:
http://developer.android.com/reference/org/json/package-summary.html

Other answers have noted Jackson and GSON - the popular add-on JSON libraries for Android, and json.org, the bare-bones JSON package that is included in Android.
But I think it is also worth noting that Android now has its own full featured JSON API.
This was added in Honeycomb: API level 11.
This comprises
- android.util.JsonReader: docs, and source
- android.util.JsonWriter: docs, and source
I will also add one additional consideration that pushes me back towards Jackson and GSON: I have found it useful to use 3rd party libraries rather then android.* packages because then the code I write can be shared between client and server. This is particularly relevant for something like JSON, where you might want to serialize data to JSON on one end for sending to the other end. For use cases like that, if you use Java on both ends it helps to avoid introducing android.* dependencies.
Or I guess one could grab the relevant android.* source code and add it to your server project, but I haven't tried that...

You can download a library from http://json.org (Json-lib or org.json) and use it to parse/generate the JSON

you just need to import this
import org.json.JSONObject;
constructing the String that you want to send
JSONObject param=new JSONObject();
JSONObject post=new JSONObject();
im using two object because you can have an jsonObject within another
post.put("username(here i write the key)","someusername"(here i put the value);
post.put("message","this is a sweet message");
post.put("image","http://localhost/someimage.jpg");
post.put("time": "present time");
then i put the post json inside another like this
param.put("post",post);
this is the method that i use to make a request
makeRequest(param.toString());
public JSONObject makeRequest(String param)
{
try
{
setting the connection
urlConnection = new URL("your url");
connection = (HttpURLConnection) urlConnection.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-type", "application/json;charset=UTF-8");
connection.setReadTimeout(60000);
connection.setConnectTimeout(60000);
connection.connect();
setting the outputstream
dataOutputStream = new DataOutputStream(connection.getOutputStream());
i use this to see in the logcat what i am sending
Log.d("OUTPUT STREAM " ,param);
dataOutputStream.writeBytes(param);
dataOutputStream.flush();
dataOutputStream.close();
InputStream in = new BufferedInputStream(connection.getInputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
result = new StringBuilder();
String line;
here the string is constructed
while ((line = reader.readLine()) != null)
{
result.append(line);
}
i use this log to see what its comming in the response
Log.d("INPUTSTREAM: ",result.toString());
instancing a json with the String that contains the server response
jResponse=new JSONObject(result.toString());
}
catch (IOException e) {
e.printStackTrace();
return jResponse=null;
} catch (JSONException e)
{
e.printStackTrace();
return jResponse=null;
}
connection.disconnect();
return jResponse;
}

if your are looking for fast json parsing in android than i suggest you a tool which is freely available.
JSON Class Creator tool
It's free to use and it's create your all json parsing class within a one-two seconds.. :D

Although there are already excellent answers are provided by users such as encouraging use of GSON etc. I would like to suggest use of org.json. It includes most of GSON functionalities. It also allows you to pass json string as an argument to it's JSONObject and it will take care of rest e.g:
JSONObject json = new JSONObject("some random json string");
This functionality make it my personal favorite.

There are different open source libraries, which you can use for parsing json.
org.json :- If you want to read or write json then you can use this library.
First create JsonObject :-
JSONObject jsonObj = new JSONObject(<jsonStr>);
Now, use this object to get your values :-
String id = jsonObj.getString("id");
You can see complete example here
Jackson databind :- If you want to bind and parse your json to particular POJO class, then you can use jackson-databind library, this will bind your json to POJO class :-
ObjectMapper mapper = new ObjectMapper();
post= mapper.readValue(json, Post.class);
You can see complete example here