question: @ Override public void handleClick ( int x , int y , PlotRenderingInfo info ) { Rectangle2D dataArea = info . getDataArea ( ) ; if ( dataArea . contains ( x , y ) ) { ValueAxis xaxis = getDomainAxis ( ) ; if ( xaxis != null ) { double hvalue = xaxis . java2DToValue ( x , info . getDataArea ( ) , getDomainAxisEdge ( ) ) ; setDomainCrosshairValue ( hvalue ) ; } ValueAxis yaxis = getRangeAxis ( ) ; if ( yaxis != null ) { double vvalue = yaxis . java2DToValue ( y , info . getDataArea ( ) , getRangeAxisEdge ( ) ) ; setRangeCrosshairValue ( vvalue ) ; } } }
target:  Handles a 'click' on the plot by updating the anchor values.