无法更改BorderLayout中块的大小

Question

我用Border Layout创建了一个简单的应用程序，向其中添加了两个按钮和JTable。我在button2和JTable之间使用了JSplitPane。我想重新定义按钮1所在块的默认大小。我该如何解决这个问题？

以下是我的代码：

package test;

import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;

public class Sample {

    public Sample() {
        JFrame app = new JFrame("Sample");
        app.setSize(new Dimension(800,600));

        JPanel panel = new JPanel();
        app.add(panel);

        BorderLayout borderlayout = new BorderLayout();
        panel.setLayout(borderlayout);

        JButton but1 = new JButton("1");
        JButton but2 = new JButton("2");
        but2.setMinimumSize(new Dimension(250,0));
        String[] colNames = {"Name","Number","Scores"};
        Object[][] data = {
                { "Mark",11,12},
                {"Tommy",23,34},
                {"John",34,45}
        };
        JTable table = new JTable(data, colNames);

        JScrollPane scrollpane = new JScrollPane(table);
        JSplitPane jsplitpane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,but2,scrollpane);

        panel.add(but1,BorderLayout.NORTH);
        panel.add(jsplitpane,BorderLayout.CENTER);

        app.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new Sample();
            }
        });
    }
}

- veinhorn

---

请您能否详细说明一下您的需求，这样别人才能更好地回答您 :-) 如果您能提供一个所需内容的图像或草图，那就足以让人了解问题的需求，并更好地指导解决方案。同时，建议您提供一个最小化、自包含且可重复的代码示例(SSCCE)，以便更好地理解和解决问题。 - nIcE cOw

Answer 1

BorderLayout.PAGE_START位置中的组件将按照其首选大小的高度进行展示。因此，您可以覆盖JButton but1的首选大小。

JButton but1 = new JButton("1") {
   public Dimension getPreferredSize() {
      return new Dimension(100, 80);
   };
};

- Reimeus

---

抱歉，我在标题中犯了一个错误。但是我能改变BorderLayout.NORTH的默认大小吗？ - veinhorn

调整高度参数，以便在默认大小和修改后的大小之间看到明显的差异。请查看小更新。 - Reimeus

似乎你只能设置高度。 - Peter Chaula

Answer 2

如果您愿意使用GridBagLayout来实现上述目的，那么我想这个Layout可以为您完成此任务，如下面粘贴的代码示例所述:-)

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Dimension;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;

public class Sample {

    public Sample() {
        JFrame app = new JFrame("Sample");
        app.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        app.setSize(new Dimension(800,600));

        JPanel panel = new JPanel();
        panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
        panel.setLayout(new BorderLayout(5, 5));
        JPanel centerPanel = new JPanel();
        centerPanel.setLayout(new GridBagLayout());        

        JButton but1 = new JButton("1");
        JButton but2 = new JButton("2");
        but2.setMinimumSize(new Dimension(250,0));
        String[] colNames = {"Name","Number","Scores"};
        Object[][] data = {
                { "Mark",11,12},
                {"Tommy",23,34},
                {"John",34,45}
        };
        JTable table = new JTable(data, colNames);

        JScrollPane scrollpane = new JScrollPane(table);
        JSplitPane jsplitpane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,but2,scrollpane);

        GridBagConstraints gbc = new GridBagConstraints();
        gbc.anchor = GridBagConstraints.FIRST_LINE_START;
        gbc.fill = GridBagConstraints.BOTH;
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.weightx = 1.0;
        gbc.weighty = 0.3;

        centerPanel.add(but1, gbc);        

        gbc.fill = GridBagConstraints.BOTH;
        gbc.gridy = 1;
        gbc.weighty = 0.7;

        centerPanel.add(jsplitpane, gbc);

        panel.add(centerPanel, BorderLayout.CENTER);

        app.add(panel);
        app.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new Sample();
            }
        });
    }
}

以下是相同代码的输出：

- nIcE cOw