@Nullable
  public Drawable getDrawable(int index) {
    Preconditions.checkArgument(index >= 0);
    Preconditions.checkArgument(index < mLayers.length);
    return mLayers[index];
  }
@ Nullable public Drawable getDrawable ( int index ) { Preconditions . checkArgument ( index >= 0 ) ; Preconditions . checkArgument ( index < mLayers . length ) ; return mLayers [ index ] ; }
Gets the drawable at the specified index.
@param index index of drawable to get
@return drawable at the specified index