JFreeChart 条形图

import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
public class BarChartExample extends JFrame {
  private static final long serialVersionUID = 1L;
  public BarChartExample(String appTitle) {
    super(appTitle);
    // Create Dataset
    CategoryDataset dataset = createDataset();
    
    //Create chart
    JFreeChart chart=ChartFactory.createBarChart(
        "Bar Chart Example", //Chart Title
        "Year", // Category axis
        "Population in Million", // Value axis
        dataset,
        PlotOrientation.VERTICAL,
        true,true,false
       );
    ChartPanel panel=new ChartPanel(chart);
    setContentPane(panel);
  }
  private CategoryDataset createDataset() {
    DefaultCategoryDataset dataset = new DefaultCategoryDataset();
    // Population in 2005
    dataset.addValue(10, "USA", "2005");
    dataset.addValue(15, "India", "2005");
    dataset.addValue(20, "China", "2005");
    // Population in 2010
    dataset.addValue(15, "USA", "2010");
    dataset.addValue(20, "India", "2010");
    dataset.addValue(25, "China", "2010");
    // Population in 2015
    dataset.addValue(20, "USA", "2015");
    dataset.addValue(25, "India", "2015");
    dataset.addValue(30, "China", "2015");
    return dataset;
  }
  public static void main(String[] args) throws Exception {
    SwingUtilities.invokeAndWait(()->{
      BarChartExample example=new BarChartExample("Bar Chart Window");
      example.setSize(800, 400);
      example.setLocationRelativeTo(null);
      example.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
      example.setVisible(true);
    });
  }
}