java中怎么调按钮的大小？？？

import javax.swing.*;
import java.awt.FlowLayout;
public class Test {
public static void main(String[]args){
JFrame a = new JFrame();
a.setVisible(true);
a.setTitle("CC");
a.setSize(420,320);
a.setLocation(200,200);
a.setResizable(true);
a.setLayout(new FlowLayout());
//
JLabel b = new JLabel("账号:");
a.add(b);
JTextField b1 = new JTextField(12);
a.add(b1);
JLabel c = new JLabel("密码:");
a.add(c);
JPasswordField c1 = new JPasswordField(12);
a.add(c1);
//
JButton d = new JButton("登陆");
a.add(d);
d.setBounds(5,5,5,5);
JButton d1 = new JButton("注册");
a.add(d1);
d1.setBounds(10,10,10,10);
a.setVisible(true);
}
}
用了 d1.setBounds(10,10,10,10); d.setBounds(5,5,5,5);按钮怎么没有变？？？

d.setSize(width, height);
或
d.setPreferredSize(new Dimension(30,30));
//（30，30） 是你要设置按钮的大小

setbounds(int x, int y, int width, int height) parameters: x the new x coordinate for the receiver y the new y coordinate for the receiver width the new width for the receiver height the new height for the receiver

用了FlowLayout不能调整大小,除非 JButton d = new JButton("登陆"); d.setPreferredSize(new Dimension(69,39)); a.add(d); 可以设置

你设成 10 和5 也太小了 怎么可能显示 import java.awt.Dimension; import java.awt.FlowLayout; import javax.swing.JButton; import javax.swing.JFrame; public class JButtonTest extends JFrame { private JButton button; public JButtonTest(){ button = new JButton("登陆"); this.setLayout(new FlowLayout(FlowLayout.CENTER, 1, 1)); Dimension preferredSize = new Dimension(300, 100); button.setPreferredSize(preferredSize ); this.setBounds(100, 100, 500, 500); this.add(button); this.setVisible(true); } public static void main(String [] args){ JButtonTest test = new JButtonTest(); } } 完整解答测试过的

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