class ActionBar extends RelativeLayout {

    @VisibleForTesting
    @Nullable
    View getViewAt(int rowIdx, int colIdx) {
        if (rowIdx < 0 || rowIdx > mRowsContainer.getChildCount()) {
            throw new IllegalArgumentException(String.format((Locale) null,
                    "Row index out of range (requested: %d, max: %d)",
                    rowIdx, mRowsContainer.getChildCount()));
        }
        if (colIdx < 0 || colIdx > mNumColumns) {
            throw new IllegalArgumentException(String.format((Locale) null,
                    "Column index out of range (requested: %d, max: %d)",
                    colIdx, mNumColumns));
        }
        FrameLayout slot = (FrameLayout) ((LinearLayout) mRowsContainer.getChildAt(rowIdx))
                .getChildAt(colIdx + 1);
        return slot.getChildCount() > 0 ? slot.getChildAt(0) : null;
    }

    public  ActionBar(Context context);
    public  ActionBar(Context context, AttributeSet attrs);
    public  ActionBar(Context context, AttributeSet attrs, int defStyleAttrs);
    public  ActionBar(Context context, AttributeSet attrs, int defStyleAttrs, int defStyleRes);

}