java - 无法在 JFrame 中显示面板

Question

我正在尝试使用 Java 设计一个计算器外壳(非功能计算器)，但由于某种原因我无法让程序显示我的按钮。我在这里做错了什么？

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

public class Calculator extends JFrame {

    public Calculator() {
        JPanel P1 = new JPanel();
        P1.setLayout(new GridLayout(4, 4));
        //Panel Buttons
        for (int i = 1; i <= 9; i++) {
            P1.add(new JButton("" + i));
        }
        P1.add(new JButton("" + 0));
        P1.add(new JButton("."));
        P1.add(new JButton("*"));
        P1.add(new JButton("/"));
        P1.add(new JButton("+"));
        P1.add(new JButton("-"));
        P1.add(new JButton("="));
        P1.setBackground(Color.cyan);
        P1.setForeground(new Color(100, 1, 1));
        //Content panel
        JPanel P2 = new JPanel();
        P2.setLayout(new BorderLayout());
        P2.add(new JTextField("Hello world"), BorderLayout.NORTH);
        P2.add(P1, BorderLayout.CENTER);
    }


    public static void main(String[] args) {
        Calculator frame = new Calculator();
        frame.setTitle("Simple Calculator");
        frame.setSize(250, 250);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

}

好的，这就是我现在所拥有的......

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

public class Calculator extends JFrame
{
JPanel p1 = new JPanel();
JPanel p2 = new JPanel();
Calculator()
{
    super("Wk 3 Calculator"); setBounds(100,100,300,100);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container con = this.getContentPane();
    con.add(p1);
    con.add(p2);
    p1.setLayout(new GridLayout(4, 4));
    //Panel Buttons
for (int i =1; i <=9; i++){
    p1.add(new JButton ("" + i));
}
    p1.add(new JButton (""+0)); 
    p1.add(new JButton ("."));      
    p1.add(new JButton ("*"));
    p1.add(new JButton ("/"));
    p1.add(new JButton ("+"));
    p1.add(new JButton ("-"));
    p1.add(new JButton ("="));
    //Content panel
    p2.setLayout(new BorderLayout());
    p2.add (new JTextField("Hello world"),BorderLayout.NORTH);
    p2.add(p1, BorderLayout.CENTER); 
    //Frame specs
    Calculator frame = new Calculator();
    frame.setSize(250,250);
    frame.setTitle("Simple Calculator");
    frame.add(p1, BorderLayout.NORTH);
    frame.add(p2, BorderLayout.SOUTH);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
}
    public static void main(String[] args){new Calculator();}           
}  

它仍然无法工作:(

Answer 1

您没有向框架添加任何内容...

尝试一些类似的事情

add(P1, BorderLayout.NORTH);
add(P2, BorderLayout.SOUTH);

对于初学者...

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• Initial Threads
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