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仅 jlabel 的鼠标单击事件正确更新 jlabel 文本属性

发布于 2024-08-11 02:07:16 字数 234 浏览 4 评论 0原文

我正在使用 java 线程来更新应用程序中的 jlabel 文本值但在更新 jlabel 上的文本之后 jlabel 通过刷新自身定期显示所有过去的更新值和新值，

但是当我在 jlabel 的 mouseclick 事件中使用相同的更新函数时，它会按我的预期更新自身，并仅显示最后一个值，

这会导致此问题我是否缺少 mouseclick 事件内部调用的一些方法？

nore：应用程序是 japplet

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醉态萌生 2024-08-18 02:07:16

不确定到底发生了什么，但我首先要确保您的更新发生在事件分派线程中。让更新程序线程调用：

SwingUtilities.invokeLater(new Runnable() {
  public void run() {
    // ...update the text...
  }
});

请参阅事件调度线程教程。

Not sure exactly what's going on but I would start by making sure your update happens in the event dispatch thread. Have your updater thread call:

SwingUtilities.invokeLater(new Runnable() {
  public void run() {
    // ...update the text...
  }
});

See the Event Dispatch Thread tutorial.

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转瞬即逝 2024-08-18 02:07:16

您必须确保对 Swing UI 组件的任何更改都在事件调度线程上执行。以下是实现此目的的两个建议：

Timer

您可能需要查看 javax.swing.Timer（如果目的是定期刷新 JLabel 文本）。计时器在事件调度线程上定期触发 ActionEvent：

  int delay = 1000; //milliseconds
  ActionListener taskPerformer = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
          label.setText("foo");
      }
  };
  new Timer(delay, taskPerformer).start();

SwingWorker

或者，您可能需要考虑使用 SwingWorker 执行后台处理。后台工作线程可以通过调用 publish 将信息传递回事件调度线程。

new SwingWorker<Void, String>() {
  // Called by the background thread.
  public Void doInBackground() {
    for (int i=0; i<100; ++i) {
      // Do work.  Periodically publish String data.
      publish("Job Number: " + i);
    }
  }

  // Called on the Event Dispatch Thread.
  @Override
  protected void process(List<String> chunks) {
    // Update label text.  May only want to set label to last
    // value in chunks (as process can potentially be called
    // with multiple String values at once).
    for (String text : chunks) {
      label.setText(text);
    }
  }  
}.execute();

You must ensure that any changes to Swing UI components are performed on the Event Dispatch Thread. Here are two suggestions for accomplishing this:

Timer

You may want to check out javax.swing.Timer if the aim is to periodically refresh the JLabel text. The timer fires ActionEvents periodically on the Event Dispatch Thread:

  int delay = 1000; //milliseconds
  ActionListener taskPerformer = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
          label.setText("foo");
      }
  };
  new Timer(delay, taskPerformer).start();

SwingWorker

Alternatively you may want to consider using a SwingWorker to perform your background processing. The background worker thread can communicate information back to the Event Dispatch thread by calling publish.

new SwingWorker<Void, String>() {
  // Called by the background thread.
  public Void doInBackground() {
    for (int i=0; i<100; ++i) {
      // Do work.  Periodically publish String data.
      publish("Job Number: " + i);
    }
  }

  // Called on the Event Dispatch Thread.
  @Override
  protected void process(List<String> chunks) {
    // Update label text.  May only want to set label to last
    // value in chunks (as process can potentially be called
    // with multiple String values at once).
    for (String text : chunks) {
      label.setText(text);
    }
  }  
}.execute();

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