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()
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