下面显示的代码将向 JFrame 添加 3 个 JLabel,然后删除这 3 个 JLabel。 2 秒后,它将重新绘制 3 个 JLabel。
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
@SuppressWarnings("serial")
public class RepaintFrameTest extends JFrame {
private JPanel panel = new JPanel();
private JLabel labelOne = new JLabel("label1");
private JLabel labelTwo = new JLabel("label2");
private JLabel labelThree = new JLabel("label3");
public RepaintFrameTest() {
panel.add(labelOne);
panel.add(labelTwo);
panel.add(labelThree);
add(panel);
pack();
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setSize(1024,768);
setLocationRelativeTo(null);
setVisible(true);
}
public static void main(String args[]) {
RepaintFrameTest frameOne = new RepaintFrameTest();
frameOne.getContentPane().removeAll();
frameOne.getContentPane().validate();
frameOne.getContentPane().repaint();
new Thread(new RepaintThread()).start();
}
}
class RepaintThread implements Runnable {
@Override
public void run() {
try {
Thread.sleep(2000);
}catch (InterruptedException interruptedException) {
System.out.println( "Thread is interrupted when it is sleeping" +interruptedException);
}
RepaintFrameTest frameTwo = new RepaintFrameTest();
frameTwo.getContentPane().validate();
frameTwo.getContentPane().repaint();
}
}
我遇到的一个小问题是它正在重新绘制新框架 (frameTwo) 而不是旧框架 (frameOne)。
如何让它重新绘制现有框架而不是重新绘制新框架?
最佳答案
- Simpy 使用 CardLayout 来交换 View 。
- 使用 Swing 计时器而不是您当前的后台线程,因为您当前的代码不是 Swing 线程安全的并且存在有害的不可预测的线程异常的风险。
- 我会给主要的 JPanel CardLayout,然后添加一个 JLabel 来保存 JPanel 和合适的字符串常量。
- 然后我将使用 JPanel 添加到主 CardLayout,这是一个在 add 方法中使用另一个 String 常量的空 JLabel。即,
add(new JLabel(), BLANK_COMPONENT);
- 然后我会在我的 Swing 计时器中简单地调用我的 CardLayout 对象上的
next()
,传入使用 CardLayout 的主要组件:cardLayout.next(myMainJPanel);
例如,
import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.event.*;
import javax.swing.*;
public class RepaintTest extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = PREF_W;
private static final int LABEL_COUNT = 3;
private static final String LABEL_PANEL = "label panel";
private static final Object BLANK_COMPONENT = "blank component";
private static final int TIMER_DELAY = 2000;
private CardLayout cardLayout = new CardLayout();
public RepaintTest() {
JPanel labelPanel = new JPanel();
for (int i = 0; i < LABEL_COUNT; i++) {
labelPanel.add(new JLabel("Label " + (i + 1)));
}
setLayout(cardLayout);
add(labelPanel, LABEL_PANEL);
add(new JLabel(), BLANK_COMPONENT);
new Timer(TIMER_DELAY, new TimerListener()).start();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private class TimerListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
cardLayout.next(RepaintTest.this);
}
}
private static void createAndShowGui() {
RepaintTest mainPanel = new RepaintTest();
JFrame frame = new JFrame("RepaintTest");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
关于java - 再次更新 JFrame,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25276474/