Question

java中点击窗口右上角的小叉号不能关闭窗口？为什么？

Answer 1

加一句setDefaultCloseOperation
默认情况下那个小叉号按钮是没有和退出程序相关联的

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;

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

public class MainClass extends JPanel {

public void paint(Graphics g) {
Dimension d = this.getPreferredSize();
int fontSize = 20;

g.setFont(new Font("TimesRoman", Font.PLAIN, fontSize));

g.setColor(Color.red);

g.drawString("www.java2s.com", 10, 20);
}

public static void main(String[] args) {
JFrame frame = new JFrame();
frame.getContentPane().add(new MainClass());

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(200,200);
frame.setVisible(true);
}
}

Answer 2

原先可以关闭么