Android page doesnot send the value to servlet. Jus shows null in servlet database table.

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Android

package com.example.jsontoservernetproject;

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

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONObject;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.app.Activity;
import com.example.jsontoservernetproject.Person;

public class MainActivity extends Activity implements OnClickListener {

	TextView tvIsConnected;
	EditText etName,etCountry,etTwitter;
	Button btnPost;

	Person person;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		// get reference to the views
		tvIsConnected = (TextView) findViewById(R.id.tvIsConnected);
		etName = (EditText) findViewById(R.id.etName);
		etCountry = (EditText) findViewById(R.id.etCountry);
		etTwitter = (EditText) findViewById(R.id.etTwitter);
		btnPost = (Button) findViewById(R.id.btnPost);
		
		// check if you are connected or not
		if(isConnected()){
			tvIsConnected.setBackgroundColor(0xFF00CC00);
			tvIsConnected.setText("You are conncted");
        }
		else{
			tvIsConnected.setText("You are NOT conncted");
		}
		
		// add click listener to Button "POST"
		btnPost.setOnClickListener(this);
		
		
	}

	public static String POST(String url, Person person){
		InputStream inputStream = null;
		String result = "";
		try {
			
			// 1. create HttpClient
			HttpClient httpclient = new DefaultHttpClient();
			
			// 2. make POST request to the given URL
		    HttpPost httpPost = new HttpPost(url);
		    
		    String json = "";
		    

		    // 3. build jsonObject
		    JSONObject jsonObject = new JSONObject();
		    jsonObject.accumulate("name", person.getName());
		    jsonObject.accumulate("country", person.getCountry());
		    jsonObject.accumulate("twitter", person.getTwitter());
		    
		    // 4. convert JSONObject to JSON to String
		    json = jsonObject.toString();

		    
			Toast.makeText(null, json,Toast.LENGTH_SHORT ).show();
		    // ** Alternative way to convert Person object to JSON string usin Jackson Lib 
		    // ObjectMapper mapper = new ObjectMapper();
		    // json = mapper.writeValueAsString(person); 
		    
		    // 5. set json to StringEntity
		    StringEntity se = new StringEntity(json);
		    
		    // 6. set httpPost Entity
		    httpPost.setEntity(se);
		    
		    // 7. Set some headers to inform server about the type of the content   
		    httpPost.setHeader("Accept", "application/json");
		    httpPost.setHeader("Content-type", "application/json");
		    
			// 8. Execute POST request to the given URL
			HttpResponse httpResponse = httpclient.execute(httpPost);
			
			// 9. receive response as inputStream
			inputStream = httpResponse.getEntity().getContent();
			
		    
			// 10. convert inputstream to string
			if(inputStream != null)
				result = convertInputStreamToString(inputStream);
			else
				result = "Did not work!";
		
		} catch (Exception e) {
			Log.d("InputStream", e.getLocalizedMessage());
		}
		
		// 11. return result
		return result;
	}
	
	 @Override
		public void onClick(View view) {
		
			switch(view.getId()){
				case R.id.btnPost:
					if(!validate())
						Toast.makeText(getBaseContext(), "Enter some data!", Toast.LENGTH_LONG).show();
					// call AsynTask to perform network operation on separate thread
					new HttpAsyncTask().execute("http://localhost:8080/JsonServer/mainPage");
				break;
			}
			
		}
	
    public boolean isConnected(){
    	ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Activity.CONNECTIVITY_SERVICE);
    	    NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
    	    if (networkInfo != null && networkInfo.isConnected()) 
    	    	return true;
    	    else
    	    	return false;	
    }
   
    private class HttpAsyncTask extends AsyncTask<string,> {
        @Override
        protected String doInBackground(String... urls) {
             
        	person = new Person();
        	person.setName(etName.getText().toString());
        	person.setCountry(etCountry.getText().toString());
        	person.setTwitter(etTwitter.getText().toString());

            return POST(urls[0],person);
        }
        // onPostExecute displays the results of the AsyncTask.
        @Override
        protected void onPostExecute(String result) {
        	Toast.makeText(getBaseContext(), "Data Sent!", Toast.LENGTH_LONG).show();
       }
    }
	
	
	private boolean validate(){
		if(etName.getText().toString().trim().equals(""))
			return false;
		else if(etCountry.getText().toString().trim().equals(""))
			return false;
		else if(etTwitter.getText().toString().trim().equals(""))
			return false;
		else
			return true;	
	}
	private static String convertInputStreamToString(InputStream inputStream) throws IOException{
        BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
        String line = "";
        String result = "";
        while((line = bufferedReader.readLine()) != null)
            result += line;
        
        inputStream.close();
        return result;
        
    }

	
}

XML:

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android">
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
 
    <textview>
        android:id="@+id/tvIsConnected"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"    
        android:removed="#FF0000"
        android:textColor="#FFF"
        android:textSize="18dp"
        android:layout_marginBottom="5dp"
        android:text="is connected?" />
 
   <relativelayout>
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
 
       <textview>
            android:id="@+id/tvName"
            android:layout_width="50dp"
            android:layout_height="wrap_content"
            android:text="Name"
            android:layout_alignBaseline="@+id/etName"/>
       <edittext>
            android:id="@+id/etName"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@+id/tvName"/>
       <textview>
            android:id="@+id/tvCountry"
            android:layout_width="50dp"
            android:layout_height="wrap_content"
            android:layout_below="@+id/tvName"
            android:text="Country"
            android:layout_alignBaseline="@+id/etCountry"/>
       <edittext>
            android:id="@+id/etCountry"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@+id/tvCountry"
            android:layout_below="@+id/etName"/>
       <textview>
            android:id="@+id/tvTwitter"
            android:layout_width="50dp"
            android:layout_height="wrap_content"
            android:layout_below="@+id/tvCountry"
            android:text="Twitter"
            android:layout_alignBaseline="@+id/etTwitter"/>
       <edittext>
            android:id="@+id/etTwitter"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@+id/tvTwitter"
            android:layout_below="@+id/etCountry"/>
   </edittext></textview></edittext></textview></edittext></textview></relativelayout>
 
   <Button
       android:id="@+id/btnPost"
       android:layout_width="200dp"
       android:layout_height="wrap_content"
       android:layout_gravity="center_horizontal"
       android:text="POST"/>
 
</textview></linearlayout>

Manifest:

<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    package="com.example.jsontoservernetproject"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk>
        android:minSdkVersion="8"
        android:targetSdkVersion="16" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

    <application>
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity>
            android:name="com.example.jsontoservernetproject.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</uses-sdk></manifest>

What I have tried:

I'm beginner to android. I have tried a Android program which sends values to servlet, In the servlet i have created database(Oracle 11g) to store received data. but unfortunately it does not receive any values, just displaying null in database table. please help me out to solve this problem.