Question

关于JAVA按钮的小程序

//目的想点击BUTTON1出现BUTTON2，点击BUTTON2出现BUTTON3
//以此类推。。。。
//问题是，点击BUTTON后并不能马上出现下一个BUTTON
//而是要拖动一下窗口才能出现0.0

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class JDefaultJFrameLayout extends JFrame {
private int buttonNum = 1;

public JDefaultJFrameLayout() {
super( "JFrame Layout Demo" );
setLayout( new FlowLayout(FlowLayout.LEFT,5,5 ) );

JButton button = new JButton("Button" + buttonNum++);
button.addActionListener(new ActionListener( ) {
public void actionPerformed( ActionEvent event ) {
JButton btn = new JButton("Button" + buttonNum++);
btn.addActionListener( this );
JDefaultJFrameLayout.this.add( btn );
JDefaultJFrameLayout.this.doLayout();
}

} );
add( button );
}

public static void main(String[] args) {
JDefaultJFrameLayout layout = new JDefaultJFrameLayout();
layout.setSize(200 , 200);
layout.setTitle("DefaultJFrameLayout");
layout.setLocationRelativeTo(null);
layout.setDefaultCloseOperation(EXIT_ON_CLOSE);
layout.setVisible(true);
}
}

Answer 1

doLayout()换成setVisible(true);