Im new to android app and trying to write my first app for learning.
But when i click on Sent To Server button app crashes :-(

here is the code
Code:
package lexcode.online;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
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.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

//import android.R.string;
import android.app.Activity;

import android.widget.*;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;

public class LexcodeActivity extends Activity implements OnClickListener {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button b = (Button) this.findViewById(R.id.submit);
        b.setOnClickListener(this);
        Button s = (Button) this.findViewById(R.id.send);
        s.setOnClickListener(this);       
        Button ss = (Button) this.findViewById(R.id.sendtoserver);
        ss.setOnClickListener(this);         
    }

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		switch ( v.getId())
		{
		case R.id.submit:
			EditText txtName = (EditText) this.findViewById(R.id.textBox);
			TextView txtStatus = (TextView) this.findViewById(R.id.response);
			String str = txtName.getText().toString();
			txtStatus.setText(str);
			break;
		case R.id.send:
			TextView txtStatus1 = (TextView) this.findViewById(R.id.textBox);
			String strRes = "Send Button Clicked ";
			txtStatus1.setText(strRes);
			break;
		case R.id.sendtoserver:
			postData();	
			TextView txtStatus11 = (TextView) this.findViewById(R.id.textBox);
			String strRes1 = "Sent to server ";
			txtStatus11.setText(strRes1);			
		}
	}
	

	    public void postData() {

	        //Create a new HttpClient and Post Header
	        HttpClient httpclient = new DefaultHttpClient();
	        HttpPost httppost = new HttpPost("http://www.mywebsite.com/save.php");
	  
	         try {
	             // Add your data
	             List <NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
	             nameValuePairs.add(new BasicNameValuePair("id", "12345"));
	             nameValuePairs.add(new BasicNameValuePair("stringdata", "AndDev is Cool!"));
	             httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
	             
	             // Execute HTTP Post Request
	             HttpResponse response = httpclient.execute(httppost);
	            
	         } catch (ClientProtocolException e) {
	        	 //e.printStackTrace();
	             // TODO Auto-generated catch block
	         } catch (IOException e) {
	        	 //e.printStackTrace();
	             // TODO Auto-generated catch block
	         } 
	 
	}
	    
	    
}