Java GridBagLayout 对齐按钮

Question

我的 GridbagLayout 有问题；我有 5 个按钮，我想以这种方式拥有它们:

我已经尝试过不同的方法，但没有人以正确的方式工作。

例如:

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestGridBagLayout {

    protected void initUI() {
        JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel southPanel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();

        gbc.gridwidth = 2;
        gbc.gridy = 0;
        JButton enterRoom = new JButton("Enter room");
        JButton exitRoom = new JButton("Exit room");
        JButton login = new JButton("Login");
        JButton logout = new JButton("Logout");
        JButton whoIsIn = new JButton("Who is in");

        gbc.gridx = 1;
        southPanel.add(enterRoom, gbc);

        gbc.gridx = 5;
        southPanel.add(exitRoom, gbc);

        gbc.gridy = 1;

        gbc.gridx = 0;
        southPanel.add(login, gbc);

        gbc.gridx = 3;
        southPanel.add(logout, gbc);

        gbc.gridx = 6;
        southPanel.add(whoIsIn, gbc);

        frame.add(southPanel);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException,
            UnsupportedLookAndFeelException {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TestGridBagLayout().initUI();
            }
        });
    }
}

出现: 我对其他方法(例如 GridLayout)不感兴趣，我想知道我缺少什么。

Answer 1

GridBagLayout 在某些情况下可能是一种奇怪的动物。但无论如何，只有在“spanned”列中存在需要一定宽度的实际组件时，gridwidth 才是有效的(例如，如果您说 gridx=0 且 gridwidth=2，则第 0 列有一个组件并且“spanned”列有一个组件)。 "列是第 1 列)。

在您的情况下，第 2、4 和 7 列没有组件，因此它们的宽度设置为 0。此外，第 5 列的宽度也为 0，因为第 6 列为退出房间按钮提供了足够的宽度，因此最终你会得到你所看到的结果。

现在，不确定您想要实现的布局类型(我看到了您的屏幕截图，但是当面板折叠/扩展宽度时它应该如何表现？)。因此，在下面找到一个更接近您所描述的示例(尽管我觉得它不是很好)

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestGridBagLayout2 {

    protected void initUI() {
        JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel southPanel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();

        gbc.gridy = 0;
        JButton enterRoom = new JButton("Enter room");
        JButton exitRoom = new JButton("Exit room");
        JButton login = new JButton("Login");
        JButton logout = new JButton("Logout");
        JButton whoIsIn = new JButton("Who is in");

        gbc.gridx = 0;
        gbc.weightx = 1.0;
        gbc.anchor = GridBagConstraints.EAST;
        southPanel.add(enterRoom, gbc);

        gbc.anchor = GridBagConstraints.WEST;
        gbc.gridx = 2;
        southPanel.add(exitRoom, gbc);

        gbc.gridy = 1;

        gbc.gridx = 0;
        southPanel.add(login, gbc);

        gbc.weightx = 0;
        gbc.gridx = 1;
        southPanel.add(logout, gbc);

        gbc.weightx = 1.0;
        gbc.anchor = GridBagConstraints.EAST;
        gbc.gridx = 2;
        southPanel.add(whoIsIn, gbc);

        frame.add(southPanel);
        frame.pack();
        frame.setSize(frame.getWidth() * 4 / 3, frame.getHeight());
        frame.setMinimumSize(frame.getSize());
        frame.setVisible(true);
    }

    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException,
            UnsupportedLookAndFeelException {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TestGridBagLayout().initUI();
            }
        });
    }
}