question: public Builder addSubButton ( Drawable drawable , int [ ] twoColors , String string ) { if ( drawables == null ) drawables = new ArrayList < > ( ) ; drawables . add ( drawable ) ; if ( colors == null ) colors = new ArrayList < > ( ) ; colors . add ( twoColors ) ; if ( strings == null ) strings = new ArrayList < > ( ) ; strings . add ( string ) ; return this ; }
target:  Add a sub button with 3 params.