怎样用JFreeChart的setToolTipGenerator()方法

我在用JFreeChart画线图的时候，想设置每个数据点的提示，可怎么设置都没用，哪位大侠能否告知？不胜感谢！
   代码如下：
     private JFreeChart createLine1(){
         dataset3=new DefaultCategoryDataset();
         for(int i=2007;i<2040;i++)
         {
             String s=String.valueOf(i);
              s=s.trim();
              s=s.substring(2);
             dataset3.addValue(Math.random() * 100, "收入", s);
             dataset3.addValue(Math.random()*100, "支出", s);
         }
          JFreeChart chart = ChartFactory.createLineChart("客户的总资产、收入、支出情况",
                                 "年份",
                                 "收入、支出（单位：万元）", 
                                 dataset3,
                                 PlotOrientation.VERTICAL,true,true,false);
          CategoryPlot plot=chart.getCategoryPlot();
          plot.setDomainGridlinePaint(Color.black);
          plot.setRangeGridlinePaint(Color.pink);
          LineAndShapeRenderer renderer=(LineAndShapeRenderer)plot.getRenderer();
          renderer.setToolTipGenerator(
                 new StandardCategoryToolTipGenerator("{0}({1})",
                 NumberFormat.getNumberInstance()));                   //就是这句不起作用
          renderer.setBaseShapesVisible(true);
          renderer.setSeriesPaint(0,Color.BLUE);
          renderer.setSeriesPaint(1,Color.yellow);
          return chart;
   }