在 Java 中，有没有办法让一组可变大小的按钮居中（使用 Swing）？

Question

我一直在尝试制作这样的 GUI：

但是，我遇到的困难是我需要使按钮的文本可变——每个按钮应该呈现一个不同的选项，该选项的文本长度可能会有所不同。虽然这本身并不困难，但我已经尝试了无数不同的东西，但我无法让按钮居中，尽管它们的文本长度。无论我尝试什么，我总是遇到以下问题之一：

• 按钮不居中（左侧有空间，但超出了右侧的窗口）
• 由于某种原因，Question 和 Goodratio 会根据按钮大小改变位置

我不知道该怎么做。有没有人对什么是最好的方法有一些有用的直觉？将不胜感激。

编辑：构造函数的代码（未正确居中），我用它来设置组件，按要求：

    public ButtonPannel(Test test)
{
    super();

    op1Button = new JButton("Option 1");
    op2Button = new JButton("Option 2");
    op3Button = new JButton("Option 3");
    questionText = new JLabel("Question");
    rightAndWrongAmount = new JLabel("rightAndWrongAmount");

    GridBagLayout gridBagLayout = new GridBagLayout();
    gridBagLayout.columnWidths = new int[]{30, 331, 0};
    gridBagLayout.rowHeights = new int[]{16, 0, 134, 35, 16, 0};
    gridBagLayout.columnWeights = new double[]{0.0, 0.0, Double.MIN_VALUE};
    gridBagLayout.rowWeights = new double[]{0.0, 0.0, 1.0, 0.0, 0.0, Double.MIN_VALUE};
    setLayout(gridBagLayout);

    JPanel panel = new JPanel();
    FlowLayout flowLayout = (FlowLayout) panel.getLayout();

    op1Button.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
        }
    });

    GridBagConstraints gbc_lblQuestion = new GridBagConstraints();
    gbc_lblQuestion.insets = new Insets(0, 0, 5, 0);
    gbc_lblQuestion.gridx = 1;
    gbc_lblQuestion.gridy = 1;
    add(questionText, gbc_lblQuestion);
    panel.add(op1Button);

    panel.add(op2Button);

    panel.add(op3Button);
    GridBagConstraints gbc_panel = new GridBagConstraints();
    gbc_panel.insets = new Insets(0, 0, 5, 0);
    gbc_panel.gridx = 1;
    gbc_panel.gridy = 3;
    add(panel, gbc_panel);

    GridBagConstraints gbc_lblNewLabel_1 = new GridBagConstraints();
    gbc_lblNewLabel_1.gridx = 1;
    gbc_lblNewLabel_1.gridy = 4;

    add(rightAndWrongAmount, gbc_lblNewLabel_1);

    op1Button.addActionListener(new InputHandler(test));
    op1Button.setActionCommand("1");
    op2Button.addActionListener(new InputHandler(test));
    op2Button.setActionCommand("2");
    op3Button.addActionListener(new InputHandler(test));
    op3Button.setActionCommand("3");

}

代码是使用 WindowBuilder 生成的。问题不在于代码，而在于使用哪个 Layout 等。

Answer 1

布局有点黑魔法和反复试验。单一布局很少能完全达到您想要的效果，因此您经常需要借助复合布局（使用多个容器和布局）来获得您想要的......

所以，基本上，这是由一个面板组成，另一个面板持有按钮（另一个面板充当“伪”内容以增加空间）

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

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 {

        public TestPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;

            add(new JLabel("Question"), gbc);
            gbc.fill = GridBagConstraints.BOTH;
            gbc.weightx = 1;
            gbc.weighty = 1;
            // This is just to act as some psudo context
            add(new FillerPane(), gbc);
            gbc.fill = GridBagConstraints.NONE;
            gbc.weightx = 0;
            gbc.weighty = 0;
            add(makeButtonPane(), gbc);
            add(new JLabel("Goodratio"), gbc);
        }

        public JPanel makeButtonPane() { 
            JPanel panel = new JPanel(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.weightx = 1;
            panel.add(new JButton("Short"));
            panel.add(new JButton("Long, long, long and lobng"));
            panel.add(new JButton("In the middle"));
            return panel;
        }

    }

    public class FillerPane extends JPanel {

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }

}

“但我希望按钮大小相同”我听到你问，当然，改变布局......

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

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 {

        public TestPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;

            add(new JLabel("Question"), gbc);
            gbc.fill = GridBagConstraints.BOTH;
            gbc.weightx = 1;
            gbc.weighty = 1;
            // This is just to act as some psudo context
            add(new FillerPane(), gbc);
            gbc.fill = GridBagConstraints.NONE;
            gbc.weightx = 0;
            gbc.weighty = 0;
            add(makeButtonPane(), gbc);
            add(new JLabel("Goodratio"), gbc);
        }

        public JPanel makeButtonPane() { 
            JPanel panel = new JPanel(new GridLayout(1, 0));
            panel.add(new JButton("Short"));
            panel.add(new JButton("Long, long, long and lobng"));
            panel.add(new JButton("In the middle"));
            return panel;
        }

    }

    public class FillerPane extends JPanel {

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }

}

您必须查看布局并考虑每个元素与其他元素的关系，根据您希望它们做什么，然后找到将帮助您实现最终结果的布局管理器并将它们组合在一起