在 Java 中,我们如何调用 invokeLater() 方法?\n


**invokeLater()** 方法是 **SwingUtilities** 类的一个 **static** 方法,可用于在 **AWT** **事件分发线程**中 **异步** 执行任务。**SwingUtilities.invokeLater()** 方法的工作原理与 **SwingUtilities.invokeAndWait()** 类似,只不过它将请求放在 **事件队列** 中并 **立即返回**。**invokeLater()** 方法不会等待 **target** 引用的 **Runnable** 中的代码块执行。

语法

public static void invokeLater(Runnable target)

示例

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class InvokeLaterTest extends Object {
   private static void print(String msg) {
      String name = Thread.currentThread().getName();
      System.out.println(name + ": " + msg);
   }
   public static void main(String[] args) {
      final JLabel label= new JLabel("Initial text");
      JPanel panel = new JPanel(new FlowLayout());
      panel.add(label);
      JFrame f = new JFrame("InvokeLater Test");
      f.setContentPane(panel);
      f.setSize(400, 300);
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      f.setLocationRelativeTo(null);
      f.setVisible(true);
      try {
         print("sleeping for 5 seconds");
         Thread.sleep(5000);
      } catch(InterruptedException ie) {
         print("interrupted while sleeping");
      }
      print("creating the code block for an event thread");
      Runnable setTextRun = new Runnable() {
         public void run() {
            try {
               Thread.sleep(100);
               print("about to do setText()");
               label.setText("New text");
            } catch(Exception e) {
               e.printStackTrace();
            }
         }
      };
      print("about to call invokeLater()");
      SwingUtilities.invokeLater(setTextRun);
      print("back from invokeLater()");
   }
}

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输出


main: sleeping for 5 seconds
main: creating the code block for an event thread 
main: about to call invokeLater() 
main: back from invokeLater() 
AWT-EventQueue-0: about to do setText()


更新于:2020-07-02

3 千以上浏览

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