question: @ Override public void drawRangeGridline ( Graphics2D g2 , CategoryPlot plot , ValueAxis axis , Rectangle2D dataArea , double value ) { Range range = axis . getRange ( ) ; if ( ! range . contains ( value ) ) { return ; } PlotOrientation orientation = plot . getOrientation ( ) ; double v = axis . valueToJava2D ( value , dataArea , plot . getRangeAxisEdge ( ) ) ; Line2D line = null ; if ( orientation == PlotOrientation . HORIZONTAL ) { line = new Line2D . Double ( v , dataArea . getMinY ( ) , v , dataArea . getMaxY ( ) ) ; } else if ( orientation == PlotOrientation . VERTICAL ) { line = new Line2D . Double ( dataArea . getMinX ( ) , v , dataArea . getMaxX ( ) , v ) ; } Paint paint = plot . getRangeGridlinePaint ( ) ; if ( paint == null ) { paint = CategoryPlot . DEFAULT_GRIDLINE_PAINT ; } g2 . setPaint ( paint ) ; Stroke stroke = plot . getRangeGridlineStroke ( ) ; if ( stroke == null ) { stroke = CategoryPlot . DEFAULT_GRIDLINE_STROKE ; } g2 . setStroke ( stroke ) ; g2 . draw ( line ) ; }
target:  Draws a grid line against the range axis.