Difference between getWindow().setBackgroundDrawable and getWindow().getDecorView().setBackgroundDrawable

Question

What is the difference between them? As far as I can see they both do the same thing.

Answer 1

If you go to sources, you will find PhoneWindow.class that have implementation of Window.setBackgroundDrawable method:

@Override
public final void setBackgroundDrawable(Drawable drawable) {
    if (drawable != mBackgroundDrawable || mBackgroundResource != 0) {
        mBackgroundResource = 0;
        mBackgroundDrawable = drawable;
        if (mDecor != null) {
            mDecor.setWindowBackground(drawable);
        }
        if (mBackgroundFallbackResource != 0) {
            mDecor.setBackgroundFallback(drawable != null ? 0 : mBackgroundFallbackResource);
        }
    }
}

As you can see, it calls different method of DecorView setWindowBackground:

public void setWindowBackground(Drawable drawable) {
    if (getBackground() != drawable) {
        setBackgroundDrawable(drawable);
        if (drawable != null) {
            drawable.getPadding(mBackgroundPadding);
        } else {
            mBackgroundPadding.setEmpty();
        }
        drawableChanged();
    }
}

Which is actually use method DecorView.setBackgroundDrawable but also provides additional logic for Window. So I would suggest you to use getWindow().setBackgroundDrawable().