getting null pointer

[sameera liyanage]

this is my main class

package com.android;


import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class Welcome extends Activity implements OnClickListener{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.welcome);
        
        Button online=(Button)findViewById(R.id.online);
        Button offline=(Button)findViewById(R.id.offline);
        Button about_us=(Button)findViewById(R.id.aboutus);
        
        online.setOnClickListener(this);
        offline.setOnClickListener(this);
        about_us.setOnClickListener(this);
           
        
    }

	@Override
	public void onClick(View v) {
		
		if(v.getId()==R.id.online){
			Intent myIntent =new Intent(this, Online.class);
			startActivity(myIntent);
		}
		if(v.getId()==R.id.offline){
			Intent myIntent =new Intent(this, Offline.class);
			startActivity(myIntent);
		}
		if(v.getId()==R.id.aboutus){
			//Intent myIntent =new Intent(this, .class);
		}
	}
}

this is online class

package com.android;


import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Toast;

public class
Online extends Activity implements OnClickListener{

		private CustomRowAdapter customRowAdapter; 
		//private ListView lv1;
		private ListView listView;
		//public String lv_class_names[]= {View.class.getName()};
		
		@Override
	    public void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);
	        setContentView(R.layout.common);
		
	        
	        
	  String[] upcomingEventData = new String[]{"Init Libraries Upcoming", "Init Components Upcoming", "Init Application Upcoming", "Channel Opened Upcoming", "Data Arrived Upcoming"};
		
	  customRowAdapter = new CustomRowAdapter(upcomingEventData);
      
	   
      listView = (ListView) findViewById(R.id.listView1);
      listView.setAdapter(customRowAdapter);  
      listView.setTextFilterEnabled(true);
      listView.setOnItemClickListener(new OnItemClickListener() {

			@Override
			public void onItemClick(AdapterView<?> arg0, View view, int position,
					long arg3) {
				// TODO Auto-generated method stub
				
				Toast.makeText(getApplicationContext(), "AAAAAAAAAAAAAAAAAAAAA "+position, Toast.LENGTH_LONG).show();
				
				Bundle bundle = new Bundle();
				bundle.putString("itemname", listView.getItemAtPosition(position).toString());
			
				Intent intent = new Intent(view.getContext(), View.class);
            intent.putExtras(bundle);
            view.getContext().startActivity(intent);
          
				
//				//USED TO SHOW POPUP MESSAGE
//    		AlertDialog.Builder adb=new AlertDialog.Builder(ListviewOnclickExample.this);
//    		adb.setTitle("LVSelectedItemExample");
//    		adb.setMessage("Selected Item is = "+lv1.getItemAtPosition(position));
//    		adb.setPositiveButton("Ok", null);
//    		adb.show();
			}
    });
      
      Button back=(Button)findViewById(R.id.Back);
      
      back.setOnClickListener(this);
      
		}
		
		
	
	private class CustomRowAdapter extends BaseAdapter
	{
		private String[] data;
		private int[] images;
		
		public CustomRowAdapter(String[] data)
		{
			this.data = data;
			//this.images = images;
		}
		
		
		@Override
		public int getCount() {
			// TODO Auto-generated method stub
			return data.length;		
			
		}

		@Override
		public Object getItem(int position) {
			// TODO Auto-generated method stub
			return null;
		}

		@Override
		public long getItemId(int position) {
			// TODO Auto-generated method stub
			return 0;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			// TODO Auto-generated method stub
			
			//This is the Generic view of the row, 
			//so if we need to do some changes , we need to do them to this view.
			
			//First check whether we need to create view/initialize
			if(convertView == null)
			{
				//View is null, which means this is the first time ListView 
				//getting the data
				LayoutInflater vi =(LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
			
				convertView = vi.inflate(R.layout.list_row, null);	
			}
			
			
			TextView txtView = (TextView)convertView.findViewById(R.id.textView1);
			txtView.setText(data[position]);
			//ImageView imgView = (ImageView)convertView.findViewById(R.id.imgPicture);
			//imgView.setImageResource(images[position]);			
			
			
			return convertView;
		}		
	
}

	@Override
	public void onClick(View v) {

		if(v.getId()==R.id.Back){
			Intent myIntent =new Intent(this, Welcome.class);
			startActivity(myIntent);
		}
		
	}}

when i click the links it gives this error

09-03 16:00:46.875: ERROR/AndroidRuntime(577): FATAL EXCEPTION: main
09-03 16:00:46.875: ERROR/AndroidRuntime(577): java.lang.NullPointerException
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at com.android.Online$1.onItemClick(Online.java:52)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at android.widget.AdapterView.performItemClick(AdapterView.java:284)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at android.widget.ListView.performItemClick(ListView.java:3382)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:1696)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at android.os.Handler.handleCallback(Handler.java:587)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at android.os.Handler.dispatchMessage(Handler.java:92)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at android.os.Looper.loop(Looper.java:123)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at android.app.ActivityThread.main(ActivityThread.java:4627)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at java.lang.reflect.Method.invokeNative(Native Method)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at java.lang.reflect.Method.invoke(Method.java:521)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
09-03 16:00:46.875: ERROR/AndroidRuntime(577):     at dalvik.system.NativeStart.main(Native Method)

but whe i print position it gives values.
so how it gives null pointer?

[Ulf Dittmer]

Which object is null?

[sameera liyanage]

I also need to know ?

[Ulf Dittmer]

We are not in a position to figure that out - you are. For example, you can print relevant values to the Log.

Also, in which line does the exception occur, meaning, which one is line 52 - the one labelled 52 in your post?

[sameera liyanage]

It gives null pointer in this line

Toast.makeText(getApplicationContext(), "AAAAAAAAAAAAAAAAAAAAA "+position, Toast.LENGTH_LONG).show();

but the position value is not null.

[Ulf Dittmer]

What does getApplicationContext() return?

What does Toast.makeText(...) return?