JButtons 消失了

Question

我是编程初学者，我正在尝试创建一个计算器，大约 1 到 2 小时前我才开始，但我遇到了一个问题，所有JButton 控件都消失了。请帮忙，我已经尝试了这么久，我只是不知道我的代码有什么问题。

代码如下：

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

public class Main {

    static void gui() {
        JPanel p = new JPanel();

        JFrame f = new JFrame("Calculator");
        f.add(p);
        f.setLayout(null);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setTitle("YEET");
        f.pack();
        f.setSize(1930, 1090);

        JButton b0 = new JButton("0");
        JButton b1 = new JButton("1");
        JButton b2 = new JButton("2");
        JButton b3 = new JButton("3");
        JButton b4 = new JButton("4");
        JButton b5 = new JButton("5");
        JButton b6 = new JButton("6");
        JButton b7 = new JButton("7");
        JButton b8 = new JButton("8");
        JButton b9 = new JButton("9");

        p.setLayout(null);

        b0.setBackground(new Color(156,207,245));
        b1.setBackground(new Color(156,207,245));
        b2.setBackground(new Color(156,207,245));
        b3.setBackground(new Color(156,207,245));
        b4.setBackground(new Color(156,207,245));
        b5.setBackground(new Color(156,207,245));
        b6.setBackground(new Color(156,207,245));
        b7.setBackground(new Color(156,207,245));
        b8.setBackground(new Color(156,207,245));
        b9.setBackground(new Color(156,207,245));

        p.add(b1);
        p.add(b1);
        p.add(b2);
        p.add(b3);
        p.add(b4);
        p.add(b5);
        p.add(b6);
        p.add(b7);
        p.add(b8);
        p.add(b9);

        b0.setVisible(true);
        b1.setVisible(true);
        b2.setVisible(true);
        b3.setVisible(true);
        b4.setVisible(true);
        b5.setVisible(true);
        b6.setVisible(true);
        b7.setVisible(true);
        b8.setVisible(true);
        b9.setVisible(true);

        p.setVisible(true);
        f.setVisible((true));
    }

    public static void main(String[] args) {
                gui();
    }
}

Answer 1

null 布局只是个坏主意。 “像素完美”布局是一种错觉。花时间学习使用布局管理 API。详情请见Laying Out Components Within a Container

GridBagLayout

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Test {

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

    public Test() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JButton b0 = new JButton("0");
        private JButton b1 = new JButton("1");
        private JButton b2 = new JButton("2");
        private JButton b3 = new JButton("3");
        private JButton b4 = new JButton("4");
        private JButton b5 = new JButton("5");
        private JButton b6 = new JButton("6");
        private JButton b7 = new JButton("7");
        private JButton b8 = new JButton("8");
        private JButton b9 = new JButton("9");

        public TestPane() {
            setLayout(new GridBagLayout());

            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridy = 3;
            gbc.gridx = 0;
            gbc.weightx = 1;
            gbc.fill = gbc.BOTH;
            gbc.gridwidth = 3;

            add(b0, gbc);

            JButton[] buttons = new JButton[]{
                b7, b8, b9,
                b4, b5, b6,
                b1, b2, b3
            };
            int row = 0;
            int col = 0;
            gbc = new GridBagConstraints();
            gbc.fill = gbc.BOTH;
            gbc.weightx = 0.3;
            for (JButton btn : buttons) {
                gbc.gridx = col;
                gbc.gridy = row;
                add(btn, gbc);

                col += 1;
                if (col > 2) {
                    row++;
                    col = 0;
                }
            }
        }


    }

}

复合布局

或者，如果GridBagLayout 很少或很多，则使用多个，例如BorderLayout 和GridLayout

import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Test {

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

    public Test() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JButton b0 = new JButton("0");
        private JButton b1 = new JButton("1");
        private JButton b2 = new JButton("2");
        private JButton b3 = new JButton("3");
        private JButton b4 = new JButton("4");
        private JButton b5 = new JButton("5");
        private JButton b6 = new JButton("6");
        private JButton b7 = new JButton("7");
        private JButton b8 = new JButton("8");
        private JButton b9 = new JButton("9");

        public TestPane() {
            setLayout(new BorderLayout());

            add(b0, BorderLayout.SOUTH);

            JPanel innerPane = new JPanel(new GridLayout(3, 3));

            JButton[] buttons = new JButton[]{
                b7, b8, b9,
                b4, b5, b6,
                b1, b2, b3
            };
            for (JButton btn : buttons) {
                innerPane.add(btn);
            }

            add(innerPane);
        }

    }

}