Problem running android HelloTabWidget example - NullPointerException on addTab()

Question

I\'ve tried the Tab Layout example, and I\'ve also fixed the few typos in the example (and added all the activities to the manifest). However, when I run it on the emulator

Answer 1

Hey do the following steps and i am sure that your problem goes out:-

Create a class HelloTabWidget.java

package com.pericent;             //this is package name
import android.app.TabActivity;
import android.content.Intent;
import android.content.res.Resources;
import android.os.Bundle;
import android.util.Log;
import android.widget.TabHost;

public class HelloTabWidget extends TabActivity  {

private String TAG="HelloTabWidget";

public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

  Resources res = getResources(); // Resource object to get Drawables
  TabHost tabHost = getTabHost();  // The activity TabHost
  TabHost.TabSpec spec;  // Resusable TabSpec for each tab
  Intent intent;  // Reusable Intent for each tab

  // Create an Intent to launch an Activity for the tab (to be reused)
  intent = new Intent().setClass(this,ArtistsActivity.class);
  Log.v(TAG,"---artist activity is called---");

  // Initialize a TabSpec for each tab and add it to the TabHost
  spec = tabHost.newTabSpec("artists").setIndicator("Artists",res.getDrawable(R.drawable.ic_tab_artists)).setContent(intent);
  tabHost.addTab(spec);


  // Do the same for the other tabs
  intent = new Intent().setClass(this,AlbumsActivity.class);
  Log.v(TAG,"---album activity is called---");
  spec = tabHost.newTabSpec("albums").setIndicator("Albums",res.getDrawable(R.drawable.ic_tab_albums)).setContent(intent);
  tabHost.addTab(spec);

  intent = new Intent().setClass(this, SongsActivity.class);
  Log.v(TAG,"---song activity is called---");
  spec = tabHost.newTabSpec("songs").setIndicator("Songs",res.getDrawable(R.drawable.ic_tab_songs)).setContent(intent);
  tabHost.addTab(spec);

  }

}

Create your second activity: ArtistActivity.java

package com.pericent;

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

public class ArtistsActivity extends Activity {
 private String TAG="ArtistsActivity";
    /** Called when the activity is first created. */
    @Override
      public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        TextView textview=new TextView(this);
        textview.setText("This is Artist Activity");
        setContentView(textview);
        Log.v(TAG,"---in artist activity---");
    }
}

Create your third activity: AlbumsActivity.java

package com.pericent;

import android.R;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class AlbumsActivity extends Activity{
    private String TAG="AlbumsActivity";
    @Override
    public void onCreate(Bundle savedInstance)
    {
        super.onCreate(savedInstance);
        TextView textview_album=new TextView(this);
        textview_album.setText("This is album activity");
        setContentView(textview_album);
        Log.v(TAG,"---in album activity---");
    }

}

Create your fourth activity: SongsActivity.java

package com.pericent;

import android.R;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class SongsActivity extends Activity{
    private String TAG="SongsActivity";
    @Override
    public void onCreate(Bundle savedInstance)
    {
        super.onCreate(savedInstance);
        TextView textview_song=new TextView(this);
        textview_song.setText("This is song activity");
        setContentView(textview_song);
        Log.v(TAG,"---in songs activity---");
    }

}

Make a folder in res/drawable In this folder make 3 XML files: the code of these files like this:-

In the above XML code we use two images, the following are images which must be save in the same folder (res/drawable).

This is the main.xml:

This is AdroidManifest:

I think this all information will help, if you have any problem then free to ask me anything. I am always feel happy to help anyone.