如何使用GUI来画一条线？

解决方法

下面的例子演示了如何使用Graphics2D类与Line2D对象的draw()方法作为参数绘制一条线。

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Line2D;
import javax.swing.JApplet;
import javax.swing.JFrame;

public class Main extends JApplet {
   public void init() {
      setBackground(Color.white);
      setForeground(Color.white);
   }
   public void paint(Graphics g) {
      Graphics2D g2 = (Graphics2D) g;
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
      RenderingHints.VALUE_ANTIALIAS_ON);
      g2.setPaint(Color.gray);
      int x = 5;
      int y = 7;
      g2.draw(new Line2D.Double(x, y, 200, 200));
      g2.drawString("Line", x, 250);
   }
   public static void main(String s[]) {
      JFrame f = new JFrame("Line");
      f.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
            System.exit(0);
         }
      });
      JApplet applet = new Main();
      f.getContentPane().add("Center", applet);
      applet.init();
      f.pack();
      f.setSize(new Dimension(300, 300));
      f.setVisible(true);
   }
}

结果

上面的代码示例将产生以下结果。

Line is displayed in a frame.