question: @ Override public void drawRangeLine ( Graphics2D g2 , CategoryPlot plot , ValueAxis axis , Rectangle2D dataArea , double value , Paint paint , Stroke stroke ) { Range range = axis . getRange ( ) ; if ( ! range . contains ( value ) ) { return ; } Rectangle2D adjusted = new Rectangle2D . Double ( dataArea . getX ( ) , dataArea . getY ( ) + getYOffset ( ) , dataArea . getWidth ( ) - getXOffset ( ) , dataArea . getHeight ( ) - getYOffset ( ) ) ; Line2D line1 = null ; Line2D line2 = null ; PlotOrientation orientation = plot . getOrientation ( ) ; if ( orientation == PlotOrientation . HORIZONTAL ) { double x0 = axis . valueToJava2D ( value , adjusted , plot . getRangeAxisEdge ( ) ) ; double x1 = x0 + getXOffset ( ) ; double y0 = dataArea . getMaxY ( ) ; double y1 = y0 - getYOffset ( ) ; double y2 = dataArea . getMinY ( ) ; line1 = new Line2D . Double ( x0 , y0 , x1 , y1 ) ; line2 = new Line2D . Double ( x1 , y1 , x1 , y2 ) ; } else if ( orientation == PlotOrientation . VERTICAL ) { double y0 = axis . valueToJava2D ( value , adjusted , plot . getRangeAxisEdge ( ) ) ; double y1 = y0 - getYOffset ( ) ; double x0 = dataArea . getMinX ( ) ; double x1 = x0 + getXOffset ( ) ; double x2 = dataArea . getMaxX ( ) ; line1 = new Line2D . Double ( x0 , y0 , x1 , y1 ) ; line2 = new Line2D . Double ( x1 , y1 , x2 , y1 ) ; } g2 . setPaint ( paint ) ; g2 . setStroke ( stroke ) ; g2 . draw ( line1 ) ; g2 . draw ( line2 ) ; }
target:  Draws a line perpendicular to the range axis.