java组件及事件处理（4）--JPanel

java组件及事件处理（4）—JPanel

import java.awt.Color;
import java.awt.Container;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JPasswordField;

public class Four extends JFrame
{
    
    
	JPanel jp1;
	JPanel jp2;
	
	JButton jb1;
	JButton jb2;
	JButton jb3;
	JButton jb4;
	
	public Four(String s)
	{
    
    
		super(s);
		
		setLayout(new FlowLayout());
		
		setBounds(400, 400, 400,400);
		
		Container conn = getContentPane();
		conn.setBackground(Color.pink);
		
		jb1 = new JButton("pink");
		jb2 = new JButton("yellow");
		jb3 = new JButton("blue");
		jb4 = new JButton("red");
		
		jp1 = new JPanel();
		jp2= new JPanel();
		
		jp1.setBackground(Color.cyan);
		jp2.setBackground(Color.green);
		
		jp1.add(jb1);
		jp1.add(jb2);
		jp2.add(jb3);
		jp2.add(jb4);
		
		add(jp1);
		add(jp2);
		setVisible(true);
		
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
	}
	public static void main(String[] args)
	{
    
    
		Four a = new Four("四");
	}
}

JPanel 相当于一个盘子，组件相当于一个一个菜肴，盘子里面可以装菜肴，所以JPanel里面可以add按钮（JButton）