JAVA 36 - プログラム倉庫

import java.awt.*;
import javax.swing.*;

public class ex36 extends JFrame {
   public static void main (String args[]) {
      new ex36();
   }

   public ex36() {
      setDefaultCloseOperation(EXIT_ON_CLOSE);
      getContentPane().add(new MyJPanel());
      setSize(800,500);
      setTitle("白い画面に赤い点を打つ");
      setVisible(true);
   }
}

class MyJPanel extends JPanel {
   public MyJPanel(){setBackground(Color.white);}
   public void paintComponent(Graphics g) {
      super.paintComponent(g);
      g.setColor(Color.red);
      g.drawLine(200,200,300,300);
   }
}