Java Swing：如何动态更改GUI

Question

我需要动态添加组件。此外，我需要动态更改布局。

Answer 1

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();  }}记住一件事是您在面板上设置了新的布局，不要忘记调用面板上的方法validate()，如果不调用此方法，则不会看到布局更改的影响。如果要通过调用来查看效果，则必须调整框架的大小。你也可以很容易像设置相同的布局FlowLayout，GridLayout和BoxLayout，但设置时BorderLayout就需要限制添加元素，所以我们首先从面板中删除所有组件remove(Component comp)方法然后通过约束添加的组件面板