Question

My Nullpointer expection has me stumped. I am getting nullpointer exception at FindViewByID. Here is my piece of code

public class numberActivity extends Activity {

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.number);

}    

ImageView portrait = (ImageView) findViewById(R.id.numberImage);
public void numberClick(View v) {   
    switch(v.getId()){
            case R.drawable.numberone:
                portrait.setImageResource(R.drawable.numbertwo);
                break;

            case R.drawable.numbertwo:
                portrait.setImageResource(R.drawable.numberthree);
                break;

        }

}

}

My number.xml is here

<ImageView
    android:id="@+id/numberImage"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/numberone" 
    android:onClick="numberClick" />

Very simple code i think, but the null pointer exception is frustrating me since last night. Any help is appreciated.

Answer 1

ImageView portrait = (ImageView) findViewById(R.id.numberImage);

This line has to be in the onCreate method.
Like this

  public class numberActivity extends Activity {

    ImageView portrait;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.number);
//This element will be found once your contentview is set
        portrait = (ImageView) findViewById(R.id.numberImage);

    }    


    public void numberClick(View v) {   
        switch(v.getId()){
                case R.drawable.numberone:
                    portrait.setImageResource(R.drawable.numbertwo);
                    break;

                case R.drawable.numbertwo:
                    portrait.setImageResource(R.drawable.numberthree);
                    break;

            }

    }