(Java) make a chart

java_chart

import org.jfree.chart.JFreeChart;
import org.jfree.chart.ChartFactory;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.chart.plot.PlotOrientation;


import javax.swing.JFrame;
import java.awt.BorderLayout;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.ChartUtilities;
import java.io.File;
import java.io.IOException;


public class Test2_1 extends JFrame{
  public static void main(String[] args) {
    Test2_1 frame = new Test2_1();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 700, 700);
    frame.setTitle("グラフサンプル");
    frame.setVisible(true);
  }

  Test2_1(){
    DefaultCategoryDataset data = new DefaultCategoryDataset();
    data.addValue(300, "America", "2005");
    data.addValue(500, "America", "2006");
    data.addValue(120, "America", "2007");

    JFreeChart chart = 
      ChartFactory.createLineChart("import",
                                   "year",
                                   "ton(t)",
                                   data,
                                   PlotOrientation.VERTICAL,
                                   true,
                                   false,
                                   false);

    ChartPanel cpanel = new ChartPanel(chart);
    getContentPane().add(cpanel, BorderLayout.CENTER);
    
    File file = new File("c:\\mdb\\filename.png");
    try {
      ChartUtilities.saveChartAsPNG(file, chart, 300, 300);
    } catch (IOException e) {
      e.printStackTrace();
    }
    
    
  }
}