出於某種原因，我的JPanel沒有顯示出來

Question

這是我的代碼

import javax.swing.*; 
import java.awt.*; 
import java.awt.Graphics; 
public class Test extends JFrame{ 
    private JButton by; 
    private JButton bn; 
    JLabel startQuestion; 

    public Test() { 
     JPanel p = new JPanel(); 
     by = new JButton("Yes"); 
     bn = new JButton("No"); 
     startQuestion = new JLabel("Would you like to start?"); 
     p.setLayout(null); 
     by.setBounds(180, 250, 70, 45); 
     bn.setBounds(250, 250, 70, 45); 
     startQuestion.setLocation(195, 240); 
     p.add(by); 
     p.add(bn); 
     add(startQuestion); 
     add(p); 
     setDefaultCloseOperation(3); 
     setSize(500, 500); 
     setVisible(true); 
    } 

    public static void main(String...args) { 
     new Test(); 
    } 
} 

有沒有語法錯誤，但是不加我的JLabel（按鍵做工精細）。我不想從null更改佈局，因爲我希望能夠定義按鈕和標籤的位置。有誰知道爲什麼這不起作用？

Answer 1

這個問題類似於JLabel won't show with JPanel.setLayout(null). Why?

要在這裏回答這個問題，加上這樣一行：

startQuestion.setBounds(150, 150, 200, 20); 

Answer 2

import javax.swing.*; 
import java.awt.*; 
import java.awt.Graphics; 
public class Test extends JFrame{ 
    private JButton by; 
    private JButton bn; 
    JLabel startQuestion; 
     public Test() { 
     JPanel p = new JPanel(); 
     by = new JButton("Yes"); 
     bn = new JButton("No"); 
     startQuestion = new JLabel("Would you like to start?"); 
     //p.setLayout(null); 
     by.setBounds(180, 250, 70, 45); 
     bn.setBounds(250, 250, 70, 45); 
     startQuestion.setLocation(195, 240); 
     p.add(by); 
     p.add(bn); 
     add(startQuestion); 
     add(p); 
     setDefaultCloseOperation(3); 
     setSize(500, 500); 
     setVisible(true); 
     } 
     public static void main(String...args) { 
     new Test(); 
    } 
} 

注：

你需要註釋setlayout(null);