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我想在程序运行时修改 JPanel 的大小，例如使用菜单项。我怎样才能达到它？或者我应该如何修改我的程序以访问内容窗格中的实时 JPanel？

编辑： 如果我为默认开始时为 400x400 的游戏场制作内容窗格。但是，如果我想在菜单中添加一个选项以将大小更改为 500x500，但又不会丢失播放器已经在播放的所有内容，该怎么办？

JFrame 类：

package me.test;

import javax.swing.JFrame;


public class Main extends JFrame {
    private static final long serialVersionUID = 1L;

public static void main(String[] args) {
    // TODO Auto-generated method stub
    new Main();
}

public Main() {

    setContentPane(new MyJPanel());

    pack();
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setLocation(100,50);
    setResizable(false);
    setVisible(true);


    }

}

我修改后的JPanel：

package me.test;

import java.awt.Dimension;

import javax.swing.JPanel;

public class MyJPanel extends JPanel {

    public MyJPanel() {
        setPreferredSize(new Dimension(400,400));
    }
}
4

2 回答 2

2

查看此代码以获取一些想法。它可以根据放置在组件本身工具栏中的操作或框架的菜单项来更改大小。

代码的要点是：

  • 在相关组件上设置首选尺寸。
  • 获取对顶级容器的引用。
  • 最后pack()是顶级容器。

在此处输入图像描述

import java.awt.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.swing.border.EmptyBorder;

public class GameSize {

    // the GUI as seen by the user (without frame)
    private JPanel gui = new JPanel(new GridBagLayout());
    Action small = new AbstractAction("Small") {

        @Override
        public void actionPerformed(ActionEvent e) {
            setSize(400, 100);
        }
    };
    Action large = new AbstractAction("Large") {

        @Override
        public void actionPerformed(ActionEvent e) {
            setSize(600, 200);
        }
    };

    private final void setSize(int w, int h) {
        gui.setPreferredSize(new Dimension(w, h));
        Container c = gui.getTopLevelAncestor();
        if (c instanceof JFrame) {
            JFrame f = (JFrame) c;
            f.pack();
        }
    }

    GameSize() {
        JToolBar tb = new JToolBar("Size");
        for (Action action : getActions()) {
            tb.add(action);
        }
        gui.add(tb);

        gui.setPreferredSize(new Dimension(200, 100));
        gui.setBackground(Color.RED);
    }

    /*
     * @return the Actions
     */
    public Action[] getActions() {
        Action[] actions = {small, large};

        return actions;
    }

    /**
     * @return the gui
     */
    public JPanel getGui() {
        return gui;
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {

            @Override
            public void run() {
                GameSize gs = new GameSize();

                JFrame f = new JFrame("Demo");
                f.add(gs.getGui());
                // Ensures JVM closes after frame(s) closed and
                // all non-daemon threads are finished
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                // See http://stackoverflow.com/a/7143398/418556 for demo.
                f.setLocationByPlatform(true);

                JMenuBar menuBar = new JMenuBar();
                f.setJMenuBar(menuBar);
                JMenu size = new JMenu("Size");
                menuBar.add(size);
                for (Action action : gs.getActions()) {
                    size.add(action);
                }

                // ensures the frame is the minimum size it needs to be
                // in order display the components within it
                f.pack();
                // should be done last, to avoid flickering, moving,
                // resizing artifacts.
                f.setVisible(true);
            }
        };
        // Swing GUIs should be created and updated on the EDT
        // http://docs.oracle.com/javase/tutorial/uiswing/concurrency
        SwingUtilities.invokeLater(r);
    }
}
于 2014-02-04T16:04:22.650 回答
0

玩弄....

import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;


public class PanelResize extends JFrame 
{
    private static final long serialVersionUID = 1L;

    public static void main(String[] args) {
        new PanelResize();
    }

    private JPanel panel;

    public PanelResize() {

        panel = new MyJPanel();
        getContentPane().add(panel);

        JMenuBar menuBar = new JMenuBar();
        JMenu menu = new JMenu("Resize");
        JMenuItem menuItem = new JMenuItem("Resize");
        menuItem.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                panel.setPreferredSize(new Dimension(500,500));
                pack();
            }
        });
        menu.add(menuItem);
        menuBar.add(menu);
        this.setJMenuBar(menuBar);

        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocation(100,50);
        setResizable(false);
        setVisible(true);
    }

}


 class MyJPanel extends JPanel {

    public MyJPanel() {
        setPreferredSize(new Dimension(400,400));
    }
}
于 2014-02-04T15:25:43.903 回答