JButtons 在悬停之前不会加载到面板上？

Question

将其放在框架上时，按钮只有在鼠标悬停在其上时才会加载，然后它们会保持正常状态。这是代码：我已经调用了 repaint() 和 revalidate() 之类的东西，但其中 none 似乎已经解决了问题。主面板和框架与 StartPanel 是分开的类。谢谢！

JButton[][] levels = new JButton[3][8]; 

public StartPanel(){
    setSize(1600, 1000);
    setLayout(null);

    int count = 1;
    int yValue = 150;
    for(int r = 0; r < 3; r++){
        for(int c = 0; c < 8; c++){
            levels[r][c] = new JButton(String.valueOf(count));
            levels[r][c].setLocation(c*190 + 80, yValue);
            levels[r][c].setSize(100, 100);
            this.add(levels[r][c]);
            count++;
        }
        yValue += 200;
    }
}



public static void main(String[] args) {
    Frame f = new Frame();
    StartPanel sp = new StartPanel();
    f.add(sp);
    f.setVisible(true);
}

public Frame() {
    setSize(1600, 1000);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLayout(null);
    setResizable(false);
}

Answer 1

避免使用 null 布局，像素完美布局是现代 ui 设计中的一种错觉。影响组件个体大小的因素太多，none 是您可以控制的。 Swing 旨在与核心的布局管理器一起工作，丢弃这些将导致无穷无尽的问题和问题，您将花费越来越多的时间来尝试纠正

网格布局

我可能建议尝试 GridLayout，结合 EmptyBorder 之类的东西，你应该能够接近你想要的东西，例如......

import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        JButton[][] levels = new JButton[3][8];

        public TestPane() {
            setBorder(new EmptyBorder(40, 40, 40, 40));
            setSize(1600, 1000);
            setLayout(new GridLayout(0, 8, 40, 40));

            int count = 1;
            int yValue = 150;
            for (int r = 0; r < 3; r++) {
                for (int c = 0; c < 8; c++) {
                    levels[r][c] = new JButton(String.valueOf(count));
                    levels[r][c].setMargin(new Insets(50, 50, 50, 50));
                    this.add(levels[r][c]);
                    count++;
                }
                yValue += 200;
            }
        }
    }

}

有关详细信息，请参阅 How to Use GridLayout

GridBagLayout

另一种解决方案可能是使用 GridBagLayout，它更灵活，但也更复杂，例如...

import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        JButton[][] levels = new JButton[3][8];

        public TestPane() {
            setSize(1600, 1000);
            setLayout(new GridBagLayout());

            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
            gbc.insets = new Insets(25, 25, 25, 25);
            gbc.fill = GridBagConstraints.BOTH;

            int count = 1;
            for (int r = 0; r < 3; r++) {
                gbc.gridx = 0;
                for (int c = 0; c < 8; c++) {
                    levels[r][c] = new JButton(String.valueOf(count));
                    levels[r][c].setMargin(new Insets(50, 50, 50, 50));
                    this.add(levels[r][c], gbc);
                    gbc.gridx++;
                    count++;
                }
                gbc.gridy++;
            }
        }
    }

}

有关详细信息，请参阅 How to Use GridBagLayout

JButtons 在悬停之前不会加载到面板上？

JButtons don't load on panel until hovered over?

java

swing

jbutton

layout-manager

null-layout-manager

网格布局

GridBagLayout