Java Swing：如何动态更改GUI

我需要动态添加组件。 而且，我需要动态地改变布局。

Answer 1

作为参考，这是一个显示基本方法validate()的sscce 。 这个更详细的示例显示了两个要求：它更改布局并动态添加组件。

 import java.awt.*; import java.awt.event.ActionEvent; import javax.swing.*; /** @see http://stackoverflow.com/questions/5750068 */ public class DynamicLayout extends JPanel { private static final LayoutManager H = new GridLayout(1, 0); private static final LayoutManager V = new GridLayout(0, 1); public DynamicLayout() { this.setLayout(H); this.setPreferredSize(new Dimension(320, 240)); for (int i = 0; i < 3; i++) { this.add(new JLabel("Label " + String.valueOf(i), JLabel.CENTER)); } } private void display() { JFrame f = new JFrame("DynamicLayout"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.add(this); JPanel p = new JPanel(); p.add(new JButton(new AbstractAction("Horizontal") { @Override public void actionPerformed(ActionEvent e) { DynamicLayout.this.setLayout(H); DynamicLayout.this.validate(); } })); p.add(new JButton(new AbstractAction("Vertical") { @Override public void actionPerformed(ActionEvent e) { DynamicLayout.this.setLayout(V); DynamicLayout.this.validate(); } })); f.add(p, BorderLayout.SOUTH); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { new DynamicLayout().display(); } }); } } 

Answer 2

动态更改布局的示例：

 package swinglayout; import java.awt.BorderLayout; import java.awt.Container; import java.awt.FlowLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; public class LayoutChanger implements ActionListener{ JButton b1; JButton b2; JButton b3; JButton b4; JButton b5; JButton b6; /** This button set the flowlayout on panel2 with left orientation */ JButton flowLayout; /** This button set the Gridlayout of 2,3 grid on panel2 */ JButton gridLayout; /** This button set the Borderlayout on panel2*/ JButton borderLayout; /** * This panel is control panel where we use button to change * layout of another panel */ JPanel panel; /** This panel contain multiple button from b1 to b6 */ JPanel panel2; JFrame frame; public LayoutChanger() { //set Default Look and Feel on frame JFrame.setDefaultLookAndFeelDecorated(true); frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); Container con = frame.getContentPane(); con.setLayout(new BorderLayout()); panel = new JPanel(); panel2 = new JPanel(); //This button are used to only showing the layout effect b1 = new JButton("HelloButton1"); b2 = new JButton("HelloButton2"); b3 = new JButton("HelloButton3"); b4 = new JButton("HelloButton4"); b5 = new JButton("HelloButton5"); b6 = new JButton("HelloButton6"); // By default panel have layout panel2.add(b1); panel2.add(b2); panel2.add(b3); panel2.add(b4); panel2.add(b5); panel2.add(b6); // Layout changer button flowLayout = new JButton("FlowLayout"); gridLayout = new JButton("GridLayout"); borderLayout = new JButton("BorderLayout"); //call Action listener on every layout changer button flowLayout.addActionListener(this); gridLayout.addActionListener(this); borderLayout.addActionListener(this); panel.add(flowLayout); panel.add(gridLayout); panel.add(borderLayout); // add layout changer button panel at a top //button panel at the center of container con.add(panel, BorderLayout.PAGE_START); con.add(panel2, BorderLayout.CENTER); frame.setVisible(true); frame.pack(); } public void actionPerformed(ActionEvent e) { //set the flowlayout on panel2 if(e.getSource() == flowLayout) { FlowLayout flow = new FlowLayout(FlowLayout.LEFT); panel2.setLayout(flow); panel2.validate(); } //set the gridlayout on panel2 if(e.getSource() == gridLayout) { GridLayout grid = new GridLayout(2,3); panel2.setLayout(grid); panel2.validate(); } //set the gridlayout but the problem if we don't set the constraint //all button are set on center. So you remove the all button from panel //Then set grid layout on panel and add them with constraints. if(e.getSource() == borderLayout) { panel2.remove(b1); panel2.remove(b2); panel2.remove(b3); panel2.remove(b4); panel2.remove(b5); panel2.remove(b6); BorderLayout border = new BorderLayout(); panel2.setLayout(border); panel2.add(b1,BorderLayout.NORTH); panel2.add(b2,BorderLayout.SOUTH); panel2.add(b3,BorderLayout.EAST); panel2.add(b4,BorderLayout.WEST); panel2.add(b5,BorderLayout.CENTER); panel2.add(b6,BorderLayout.BEFORE_FIRST_LINE); panel2.validate(); } } public static void main(String args[]) { new LayoutChanger(); } } 

有一点需要记住，你在面板上设置了新的布局，不要忘记在面板上调用方法validate() 。如果你不调用这个方法，你就看不到布局变化的影响了。 如果您想要通过调用方法来查看效果，则必须调整框架的大小。 你也可以很容易地设置相同的布局，如FlowLayout ， GridLayout和BoxLayout ，但是当设置BorderLayout它需要添加元素的约束，所以我们首先通过remove(Component comp)方法从面板中删除所有组件，然后通过约束在面板中添加组件