question: public void previous ( ControllerAnimator animator ) { if ( animator == null ) throw new NullPointerException ( "Animator cannot be null" ) ; if ( iterator . hasPrevious ( ) ) { View currentView = mViews . get ( iterator . nextIndex ( ) ) ; if ( iterator . nextIndex ( ) > 0 ) { View previousView = iterator . previous ( ) ; if ( isUsingDefaultListener ( ) ) previousView . setOnClickListener ( listener ) ; animator . setOldView ( currentView ) ; animator . setNewView ( previousView ) ; currentView . startAnimation ( animator ) ; } } else { if ( mLoop ) { iterator = mViews . listIterator ( ) ; for ( int i = 0 ; i < mViews . size ( ) - 1 ; i ++ ) { iterator . next ( ) ; } View currentView = mViews . get ( 0 ) ; View previousView = mViews . get ( mViews . size ( ) - 1 ) ; if ( mUseDefaultListener ) previousView . setOnClickListener ( listener ) ; animator . setOldView ( currentView ) ; animator . setNewView ( previousView ) ; currentView . startAnimation ( animator ) ; } } }
target:  Go back to the previous view