Java Swing JPanel

Java Swing教程 - Java Swing JPanel

JPanel是用于其他组件的容器。我们可以设置其布局管理器，边框和背景颜色。JPanel组相关组件。

Java Swing教程 - Java Swing JPanel...

下表列出了JPanel类的构造函数。

以下代码显示如何使用BorderLayout创建JPanel并向其添加按钮。

import java.awt.BorderLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;


public class Main {
  public static void main(String[] args) {
    JFrame frame = new JFrame("JFrame");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel buttonPanel = new JPanel(new BorderLayout()); 
    JButton northButton = new JButton("North");
    JButton southButton = new JButton("South"); 
    JButton eastButton  = new JButton("East"); 
    JButton  westButton = new JButton("west");

    buttonPanel.add(northButton, BorderLayout.NORTH); 
    buttonPanel.add(southButton, BorderLayout.SOUTH); 
    buttonPanel.add(eastButton,  BorderLayout.EAST); 
    buttonPanel.add(westButton,  BorderLayout.WEST);

    frame.add(buttonPanel,  BorderLayout.CENTER);
     

    frame.pack();
    frame.setVisible(true);
  }
}

使用JPanel作为画布

import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main extends JPanel {
  public Main() {
  }
  public void paintComponent(Graphics g) {
    int width = getWidth();
    int height = getHeight();
    g.setColor(Color.black);
    g.drawOval(0, 0, width, height);
  }
  public static void main(String args[]) {
    JFrame frame = new JFrame("Oval Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new Main());
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}