如何使用菜单在Java秋千的不同布局之间切换

Question

我想制作一个没有默认布局的jpanel的应用。我希望能够使用菜单中的选项更改布局。例如，如果我有一个控件将三个图像图标添加到jpanel，则这些图标的大小和位置应由框架的当前布局管理器确定。因此，如果我在边框布局中添加3个图像图标(在南部，东部和中心位置添加它们(，将布局切换到流程布局应该使它们在没有调整大小的情况下以右至左顺序出现。

我对如何解决这个问题感到困惑。有没有办法在同一JPanel中切换布局？

Answer 1

在每个菜单操作之后动态更改布局，设置带有约束的新布局，然后调用Revalidate((方法。检查以下代码的ActionPerformed((方法。

public class LayoutController extends JFrame implements ActionListener {
    JMenuItem flowLayout;
    JMenuItem borderLayout;
    JMenuItem gridLayout;
    JPanel panel;
    JButton button1;
    JButton button2;
    JButton button3;
    public LayoutController() {
        setSize(600, 600);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        panel = new JPanel();
        panel.setLayout(null); // no default layout
        panel.setSize(600, 600);
        flowLayout = new JMenuItem("Flow Layout");
        flowLayout.addActionListener(this);
        borderLayout = new JMenuItem("Border Layout");
        borderLayout.addActionListener(this);
        gridLayout = new JMenuItem("Grid Layout");
        gridLayout.addActionListener(this);
        // menu to change layout dynamically
        JMenu fileMenu = new JMenu("Layout");
        fileMenu.add(flowLayout);
        fileMenu.add(borderLayout);
        fileMenu.add(gridLayout);
        JMenuBar menuBar = new JMenuBar();
        menuBar.add(fileMenu);
        setJMenuBar(menuBar);
        // Customize your components
        button1 = new JButton("IMAGE1");
        button2 = new JButton("IMAGE2");
        button3 = new JButton("IMAGE3");
        panel.add(button1);
        panel.add(button2);
        panel.add(button3);
        add(panel, BorderLayout.CENTER);
    }
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new LayoutController().setVisible(true);
            }
        });
    }
    @Override
    public void actionPerformed(ActionEvent e) {
        //Customize your code here
        if (e.getSource() == flowLayout) {
            //flow layout with right alignment
            panel.setLayout(new FlowLayout(FlowLayout.RIGHT));
        } else if (e.getSource() == borderLayout) {
            // border layout with constraints
            BorderLayout layout = new BorderLayout();
            layout.addLayoutComponent(button1, BorderLayout.SOUTH);
            layout.addLayoutComponent(button2, BorderLayout.EAST);
            layout.addLayoutComponent(button3, BorderLayout.CENTER);
            panel.setLayout(layout);
        } else if (e.getSource() == gridLayout) {
            // grid layout with 2 rows and 2 columns
            panel.setLayout(new GridLayout(2, 2));
        }
        panel.revalidate();
    }
}