Java 示例 - 使用 GUI 显示多边形

• 

  问题描述

  如何使用 GUI 绘制多边形？
• 

  解决方案

  以下示例演示如何通过创建 Polygon() 对象来绘制多边形。addPoint() & drawPolygon() 方法用于绘制多边形。

  
  import java.awt.*;
  import java.awt.event.*;
  import javax.swing.*;
  public class Main extends JPanel {
     public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Polygon p = new Polygon();
        for (int i = 0; i < 5; i++) p.addPoint((int) (
           100 + 50 * Math.cos(i * 2 * Math.PI / 5)),(int) (100 + 50 * Math.sin(
           i * 2 * Math.PI / 5)));
        g.drawPolygon(p);
     }
     public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setTitle("Polygon");
        frame.setSize(350, 250);
        
        frame.addWindowListener(new WindowAdapter() {
           public void windowClosing(WindowEvent e) {
              System.exit(0);
           }
        });
        Container contentPane = frame.getContentPane();
        contentPane.add(new Main());
        frame.setVisible(true);
     }
  }
  

• 

  结果

  上面的代码示例将产生以下结果。

  
  Polygon is displayed in a frame.
  

  下面是另一个使用 GUI 绘制多边形的示例。

  
  import java.awt.Color;
  import java.awt.Container;
  import java.awt.Graphics;
  import java.awt.Polygon;
  import java.awt.event.WindowAdapter;
  import java.awt.event.WindowEvent;
  import javax.swing.JFrame;
  import javax.swing.JPanel;
  public class Panel extends JPanel {
     public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Polygon p = new Polygon();
        for (int i = 0; i < 5; i++) p.addPoint((int) (
           100 + 50 * Math.cos(i * 2 * Math.PI / 5)),(int) (
           100 + 50 * Math.sin(i * 2 * Math.PI / 5)));
        
        g.drawPolygon(p);
     } 
     public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.getContentPane().setBackground(Color.YELLOW); 
        frame.setTitle("DrawPoly");
        frame.setSize(350, 250);
        frame.addWindowListener(new WindowAdapter() {
           public void windowClosing(WindowEvent e) {
              System.exit(0);
           } 
        }); 
        Container contentPane = frame.getContentPane();
        contentPane.add(new Panel());
        frame.show();
     }
  }
  

  上面的代码示例将产生以下结果。

  
  Polygon is displayed in a frame.