如何使按钮扩展Java

Question

我正在尝试创建一个Java Applet，我在Java网站上四处寻找，发现了一个我编辑过的很好的例子。

在本例中有3个按钮，一个类似于页眉，一个类似于页脚，另一个类似于正文。我的问题是，中间(正文)按钮不会完全展开。

如果你运行这段代码，你就会明白我的意思。

import java.awt.*;
import javax.swing.JButton;
import javax.swing.JFrame;

public class main {
    final static boolean shouldFill = true;
    final static boolean shouldWeightX = true;
    final static boolean RIGHT_TO_LEFT = false;

    public static void addComponentsToPane(Container pane) {
        if (RIGHT_TO_LEFT) {
            pane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
        }

        JButton button;
    pane.setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();
    if (shouldFill) {
    //natural height, maximum width
    c.fill = GridBagConstraints.HORIZONTAL;
    }


    button = new JButton("hi");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.weightx = 0.5;
    c.gridx = 1;
    c.gridy = 0;
    c.ipady = 40;
    pane.add(button, c);

    button = new JButton("Hello, i will not expand");
    c.fill = GridBagConstraints.BOTH;
    c.weighty = 1.0;   //request any extra vertical space
    c.weightx=1.0;
    c.anchor = GridBagConstraints.CENTER; //bottom of space
    c.insets = new Insets(10,0,0,0);  //top padding
    c.gridx = 1;       //aligned with button 2
    c.gridy = 1;       //third row
    pane.add(button, c);


    button = new JButton("fr");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipady = 0;       //reset to default
    c.weighty = 1.0;   //request any extra vertical space
    c.anchor = GridBagConstraints.PAGE_END; //bottom of space
    c.insets = new Insets(10,0,0,0);  //top padding
    c.gridx = 1;       //aligned with button 2
    c.gridwidth = 2;   //2 columns wide
    c.gridy = 2;       //third row
    pane.add(button, c);
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("main");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Set up the content pane.
        addComponentsToPane(frame.getContentPane());

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

​

​

Answer 1

看起来这不是中间按钮的问题，而是底部按钮没有展开，如果你将底部按钮设置为so c.fill = GridBagConstraints.BOTH;，那么它会占用下面的空白空间。

你想让中间再大一点吗？您可能希望将底部按钮的权重更改为.5 c.weighty = .5; //request any extra vertical space

看看这是不是你要找的？

如果你希望中间比顶部和底部大得多，你可能需要创建更多的网格空间，所以不是1,1,1，而是1,3,1，等等

Answer 2

我在

网站上找了看，发现了一个很好的例子，我编辑了一下。

所以我想你不用用GridBagLayout了吧？

使用BorderLayout，使位置为BorderLayout.CENTER的可展开按钮。

http://docs.oracle.com/javase/tutorial/uiswing/layout/border.html