question: protected void drawRangeGridlines ( Graphics2D g2 , Rectangle2D dataArea , List ticks ) { if ( ! isRangeGridlinesVisible ( ) && ! isRangeMinorGridlinesVisible ( ) ) { return ; } ValueAxis axis = getRangeAxis ( ) ; if ( axis == null ) { return ; } CategoryItemRenderer r = getRenderer ( ) ; if ( r == null ) { return ; } Stroke gridStroke = null ; Paint gridPaint = null ; boolean paintLine ; Iterator iterator = ticks . iterator ( ) ; while ( iterator . hasNext ( ) ) { paintLine = false ; ValueTick tick = ( ValueTick ) iterator . next ( ) ; if ( ( tick . getTickType ( ) == TickType . MINOR ) && isRangeMinorGridlinesVisible ( ) ) { gridStroke = getRangeMinorGridlineStroke ( ) ; gridPaint = getRangeMinorGridlinePaint ( ) ; paintLine = true ; } else if ( ( tick . getTickType ( ) == TickType . MAJOR ) && isRangeGridlinesVisible ( ) ) { gridStroke = getRangeGridlineStroke ( ) ; gridPaint = getRangeGridlinePaint ( ) ; paintLine = true ; } if ( ( ( tick . getValue ( ) != 0.0 ) || ! isRangeZeroBaselineVisible ( ) ) && paintLine ) { if ( r instanceof AbstractCategoryItemRenderer ) { AbstractCategoryItemRenderer aci = ( AbstractCategoryItemRenderer ) r ; aci . drawRangeLine ( g2 , this , axis , dataArea , tick . getValue ( ) , gridPaint , gridStroke ) ; } else { r . drawRangeGridline ( g2 , this , axis , dataArea , tick . getValue ( ) ) ; } } } }
target:  Draws the range gridlines for the plot, if they are visible.