Android SurfaceView : cannot build when add callback

Question

I have implemented custom Android SurfaceView and meet error when I add callback for it.

Here is my code for class SurfaceView:

public class AndroidSurface extends SurfaceView {

    public SurfaceHolder holder;

    public AndroidSurface(Context context, AttributeSet attrs) {
        super(context, attrs);

        holder = getHolder();
        holder.addCallback(new SurfaceHolder.Callback() {

            public void surfaceChanged(SurfaceHolder holder, int format,
                    int width, int height) {
                // TODO Auto-generated method stub

            }

            public void surfaceCreated(SurfaceHolder holder) {
                // TODO Auto-generated method stub

            }

            public void surfaceDestroyed(SurfaceHolder holder) {
                // TODO Auto-generated method stub

            }


        });
    }
}

When I add this view to layout.xml, for example :

<com.app.AndroidSurface
        android:id="@+id/surfaceView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/rightBtn"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/textView1" />

I will met error when show in Graphical Layout : failed to instantiate. (at Plugin : com.android.ide.eclipse.adt) and when run this project, I will have exception. When view in LogCat, I see that Java Null Point Exception.

The strange thing is : if I remove holder.addCallback(new SurfaceHolder.Callback() {... no error met.

This looks strange too me, please tell me how to fixed this.

@ Edited : and the problem because when I getHolder, it doesn't return surface holder, so holder is null, I don't know why.

Thanks :)

Post the logcat. Check if the holder is null. Click on the line where you package name is shown in red. This will take to exactl stop. — Code Droid, Aug 06 '12 at 18:04
You can also debug and set a breakpoint on the holder to see if it is null. — Code Droid, Aug 06 '12 at 18:05
@CodeDroid oh, yes, you right, `holder`is null, and I don't think this before. But, why it is null, please help me. Thanks :) — hqt, Aug 06 '12 at 18:11
If you wrote it, you should know what is returning null or how its null. — JoxTraex, Aug 06 '12 at 18:19
Oh. I have a silly mistake, when I create this class, I have created a getter with this which name is : `getHolder`, that why my program went wrong !!! — hqt, Aug 06 '12 at 18:25

score 0 · Accepted Answer · edited May 23 '17 at 11:59

0

You should check your context and make sure you are doing things in the correct order with respect to your lifecycle. Check out this post surfaceView.getHolder not returning SurfaceHolder

edited May 23 '17 at 11:59

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answered Aug 06 '12 at 18:20

Frank Sposaro

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Android SurfaceView : cannot build when add callback

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