Java 在Jfreechart中更改图形的X轴起始值的步骤

我正在计算图像红色分量的直方图，并将其存储在redhisto[]中。数组的索引表示强度（0到255） 该值表示具有该强度的像素数。然后用JFreeChart绘制这些值

我的问题是:

如何使X轴值从0开始。现在它从负数开始

我们能改变图表中条形图的颜色吗 代码是：

 public class Histogram extends ApplicationFrame {
   public Histogram(final String title) throws IOException {
    super(title);
    IntervalXYDataset dataset = createDataset();
    JFreeChart chart = createChart(dataset);
    final ChartPanel chartPanel = new ChartPanel(chart);
    chartPanel.setPreferredSize(new java.awt.Dimension(500, 270));
    setContentPane(chartPanel);
   }

  private IntervalXYDataset createDataset() throws IOException {
   BufferedImage imageA = ImageIO.read(new File("XYZ.bmp"));
   int[] red = new int[imageA.getHeight()*imageA.getWidth()];
   int[] redhisto = new int[256];
   int[] pixel;
   int k= 0;
   for (int y = 0; y < imageA.getHeight(); y++) {
      for (int x = 0; x < imageA.getWidth(); x++) {
        pixel = imageA.getRaster().getPixel(x, y, new int[3]);       
        red[k] = pixel[0];
        k++;
      }
   }        

   for(int x=0;x<red.length;x++){
       int y = red[x];
       redhisto[y]++;
    }

  final XYSeries series = new XYSeries("No of pixels");
  for(int i=0; i<redhisto.length;i++)
    series.add(i,redhisto[i]);

  final XYSeriesCollection dataset = new XYSeriesCollection(series);
  return dataset;
 }

 private JFreeChart createChart(IntervalXYDataset dataset) {
  final JFreeChart chart = ChartFactory.createXYBarChart("Color Intensity   Histogram","X",false,"Y",dataset,PlotOrientation.VERTICAL,true,true,false);
  XYPlot plot = (XYPlot) chart.getPlot();
  return chart;    
 }

 public static void main(final String[] args) throws IOException {
  final Histogram demo = new Histogram("Image Histogram");
  demo.pack();
  RefineryUtilities.centerFrameOnScreen(demo);
  demo.setVisible(true);
 }
}

公共类直方图扩展了ApplicationFrame{
公共直方图（最终字符串标题）引发IOException{
超级（标题）；
IntervalXYDataset数据集=createDataset（）；
JFreeChart chart=createChart（数据集）；
最终图表面板图表面板=新图表面板（图表）；
setPreferredSize（新java.awt.Dimension（500270））；
setContentPane（图表面板）；
}
私有IntervalXYDataset createDataset（）引发IOException{
BuffereImage imageA=ImageIO.read（新文件（“XYZ.bmp”）；
int[]red=新int[imageA.getHeight（）*imageA.getWidth（）]；
int[]redhisto=新int[256]；
int[]像素；
int k=0；
对于（int y=0；y对于（int x=0；x您可以更改域轴的下限，并按如下所示设置系列绘制。默认的
XYBarPainter
具有渐变色高亮显示，因此我使用了
StandardXYBarPainter

XYPlot plot = (XYPlot) chart.getPlot();
ValueAxis axis = plot.getDomainAxis();
axis.setLowerBound(0);
XYBarRenderer r = (XYBarRenderer) plot.getRenderer();
r.setBarPainter(new StandardXYBarPainter());
r.setSeriesPaint(0, Color.blue);


    XYPlot plot = (XYPlot) chart.getPlot();  

    //To change the lower bound of X-axis
    NumberAxis xAxis = (NumberAxis) plot.getDomainAxis();
    xAxis.setLowerBound(0);

    //To change the lower bound of Y-axis       
    NumberAxis yAxis = (NumberAxis) plot.getRangeAxis();
    yAxis.setLowerBound(0);

    // To change the color
    XYItemRenderer renderer = plot.getRenderer();
    renderer.setSeriesPaint(0, Color.green);