Get Drawable from image view

Issue

When I do the clip drawable example described in this document ImageView.getDrawable always return null. Can anyone pls help me?

In MainActivity.java onCreate

@Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ImageView imageview = (ImageView) findViewById(R.id.image);
        ClipDrawable drawable = (ClipDrawable) imageview.getDrawable();
        drawable.setLevel(drawable.getLevel() + 1000); //Line number 21
    }

Logcat

 02-04 12:16:31.156: E/AndroidRuntime(4611): FATAL EXCEPTION: main02-04 12:16:31.156: E/AndroidRuntime(4611): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test/com.example.test.MainActivity}: java.lang.NullPointerException

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.app.ActivityThread.access$1500(ActivityThread.java:117)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.os.Handler.dispatchMessage(Handler.java:99)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.os.Looper.loop(Looper.java:123)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.app.ActivityThread.main(ActivityThread.java:3683)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at java.lang.reflect.Method.invokeNative(Native Method)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at java.lang.reflect.Method.invoke(Method.java:507)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at dalvik.system.NativeStart.main(Native Method)

02-04 12:16:31.156: E/AndroidRuntime(4611): Caused by: java.lang.NullPointerException

02-04 12:16:31.156: E/AndroidRuntime(4611):      at com.example.test.MainActivity.onCreate(MainActivity.java:21)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

02-04 12:16:31.156: E/AndroidRuntime(4611):      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)

02-04 12:16:31.156: E/AndroidRuntime(4611):      ... 11 more

Solution

You have to override onWindowsFocusChanged()

 @Override
 public void onWindowFocusChanged(boolean hasWindowFocus) {
    super.onWindowFocusChanged(hasWindowFocus);
   ClipDrawable drawable = (ClipDrawable) imageview.getBackground();
    drawable.setLevel(drawable.getLevel() + 1000); //Line number 21
 }

the imageView was not yet displayed properly when you tried to get its value(drawable image). onWindowsFocusChanged() will inform the user that the view has been loaded already that's the time you can get its data.

Answered By - She Smile GM