question: public int moveIndex ( int delta ) { int x = Math . max ( 0 , Math . min ( getIndex ( ) + delta , getLength ( ) ) ) ; setIndex ( x ) ; return x ; }
target:  Moves the current position by the number of code units specified, either forward or backward depending on the sign of delta (positive or negative respectively).  If the resulting index would be less than zero, the index is set to zero, and if the resulting index would be greater than limit, the index is set to limit.