How to get Bitmap from default resource for Android?

Question

Hi, I am doing this using this method.

Bitmap bm = BitmapFactory.decodeResource(getResources(), android.R.drawable.list_selector_background); int c = bm.getPixel(bm.getWidth()/2, bm.getHeight()/2); 

but bm is null , which gives a NullPointerException in the second line.

Mistake:

 02-12 18:29:57.568: E/AndroidRuntime(5086): at android.app.ActivityThread.access$600(ActivityThread.java:123) 02-12 18:29:57.568: E/AndroidRuntime(5086): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 02-12 18:29:57.568: E/AndroidRuntime(5086): at android.os.Handler.dispatchMessage(Handler.java:99) 02-12 18:29:57.568: E/AndroidRuntime(5086): at android.os.Looper.loop(Looper.java:137) 02-12 18:29:57.568: E/AndroidRuntime(5086): at android.app.ActivityThread.main(ActivityThread.java:4424) 02-12 18:29:57.568: E/AndroidRuntime(5086): at java.lang.reflect.Method.invokeNative(Native Method) 02-12 18:29:57.568: E/AndroidRuntime(5086): at java.lang.reflect.Method.invoke(Method.java:511) 02-12 18:29:57.568: E/AndroidRuntime(5086): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 02-12 18:29:57.568: E/AndroidRuntime(5086): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 02-12 18:29:57.568: E/AndroidRuntime(5086): at dalvik.system.NativeStart.main(Native Method) 02-12 18:29:57.568: E/AndroidRuntime(5086): Caused by: java.lang.NullPointerException 02-12 18:29:57.568: E/AndroidRuntime(5086): at com.example.showhide.MainActivity.onCreate(MainActivity.java:38) 02-12 18:29:57.568: E/AndroidRuntime(5086): at android.app.Activity.performCreate(Activity.java:4465) 02-12 18:29:57.568: E/AndroidRuntime(5086): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 02-12 18:29:57.568: E/AndroidRuntime(5086): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 

Answer 1

This is because this resource is StateListDrawable, not Bitmap. You should use:

  Drawable d = getResources().getDrawable(android.R.drawable.list_selector_background); 

If you are sure this is a bitmap, drop it onto BitmapDrawable and get the bitmap from here:

 Drawable currentState = d.getCurrent(); if(currentState instanceof BitmapDrawable) Bitmap b = ((BitmapDrawable)currentState).getBitmap(); 

The bitmap can also be null.

Answer 2

You should use Resources.getSystem() instead of getResources

 Bitmap bm = BitmapFactory.decodeResource(Resources.getSystem(), android.R.drawable.list_selector_background); 

Because the resource you are trying to access is not in your own resources, but in the system.

Edit:

Next to the wrong resources, you are trying to get an available resource that is a selector (xml file). Please select the desired resource :) http://androidxref.com/4.1.1/xref/frameworks/base/core/res/res/drawable/list_selector_background.xml

Answer 3

Without using BitmapFactory:

 Bitmap bmp = ((BitmapDrawable) context.getResources() .getDrawable(R.drawable.list_selector_background)).getBitmap();