Java/Swing：尝试让 BorderLayout 与 GridBagLayout 配合良好

Question

我想要一个有 3 个菜单的窗口，一个连接到左侧，另一个连接到中间，最后一个连接到右侧。像这样：

--------------------------------------------
-toolbar1---------toolbar2---------toolbar3-
--------------------------------------------
-                                          -
-  rest of the window does something here  -

我遇到的问题是这是我得到的结果：

--------------------------------------------
---------toolbar1toolbar2toolbar3-----------
--------------------------------------------
-                                          -
-  rest of the window does something here  -

这是一些示例代码（编译并显示问题）：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;


public class TestClass extends JFrame {

    public TestClass() {
        super("test");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        final JPanel upper = new JPanel();
        upper.setLayout(new GridBagLayout());
        final GridBagConstraints gbc = new GridBagConstraints();

        final JButton toolbar1 = new JButton("toolbar1");
        final JButton toolbar2 = new JButton("toolbar2");
        final JButton toolbar3 = new JButton("toolbar3");

        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.anchor = GridBagConstraints.WEST;
        upper.add(toolbar1, gbc);

        gbc.gridx = 1;
        gbc.anchor = GridBagConstraints.CENTER;
        upper.add(toolbar2, gbc);

        gbc.gridx = 2;
        gbc.anchor = GridBagConstraints.EAST;
        upper.add(toolbar3, gbc);

        add(upper, BorderLayout.NORTH);

        final JPanel something = new JPanel();
        something.setBackground(Color.WHITE);
        something.setPreferredSize(new Dimension(600, 600));
        something.repaint();
        add(something, BorderLayout.CENTER);

        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    public static void main(String[] args) {
        final TestClass test = new TestClass();
    }
}

我该如何修复它？我认为通过在 GridBagConstraints 中设置 anchor 我可以处理它，但这不起作用。

Answer 1

您忘记添加：

gbc.weightx = 1.0;
gbc.weighty = 1.0;

您更改后的代码应该如下所示：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;


public class TestClass extends JFrame {

    public TestClass() {
        super("test");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        final JPanel upper = new JPanel();
        GridBagLayout gridbag = new GridBagLayout();
        upper.setLayout(gridbag);
        GridBagConstraints gbc = new GridBagConstraints();

        final JButton toolbar1 = new JButton("toolbar1");
        final JButton toolbar2 = new JButton("toolbar2");
        final JButton toolbar3 = new JButton("toolbar3");

        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.weightx = 1.0;
        gbc.weighty = 1.0;
        gbc.anchor = GridBagConstraints.WEST;
        upper.add(toolbar1, gbc);


        gbc.gridx = 1;
        gbc.anchor = GridBagConstraints.CENTER;
        upper.add(toolbar2, gbc);


        gbc.gridx = 2;
        gbc.anchor = GridBagConstraints.EAST;
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        upper.add(toolbar3, gbc);


        add(upper, BorderLayout.NORTH);

        final JPanel something = new JPanel();
        something.setBackground(Color.WHITE);
        something.setPreferredSize(new Dimension(600, 600));
        something.repaint();
        add(something, BorderLayout.CENTER);

        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    public static void main(String[] args) {
        final TestClass test = new TestClass();
    }
}

它可以工作。

Answer 2

如果您的工具栏看起来像 BorderLayout（WEST、CENTER、EAST），为什么不使用 BorderLayout 而不是 GridBagLayout？

无论如何，如果您坚持使用GridBagLayout，请将toolbar2 的weightx 约束设置为1。这告诉布局管理器，如果有更多空间可用，则应将其全部分配给toolbar2。

  gbc.weightx = 1;
  upper.add(toolbar2, gbc);
  gbc.weightx = 0;