我可以通过Java中的Thread更改标签的文本吗? [英] Can I change the text of a label from a Thread in Java?

问题描述

我对这个论坛还有另一个问题.我正在用Java编写一个小型应用程序，其中有多个线程.我有两个不同类的两个线程.我有一个专用于定义所有JFrame组件的线程( thread1 ). (JPanels，JButton，ActionListeners等)，在另一个线程( thread2 )中，我正在检查变量( v )是否等于某个值. ( 98 )当此变量确实更改为等于 98 时，该相同线程应该会更新JLabel. (现在我们将此标签称为 label .)事实并非如此.我做错了什么吗?我尝试为该类编写一个方法-声明所有JFrame组件-更改 label 的文本，但是当我从 thread2 调用此方法时，它不会更新标签.我尝试调用包含 thread1 的超类，但这似乎没有什么不同.另外，我一直在调用 repaint()方法，但这似乎无济于事.

I have another question for this forum. I am writing a small application with Java in which I have multiple Threads. I have two Threads that are in two different classes. I have one Thread (thread1) dedicated to defining all of the JFrame components. (JPanels, JButtons, ActionListeners, etc.) In another Thread, (thread2) I am checking for a variable (v) to equal a certain value. (98) When this variables does change to equal 98, that same thread is supposed to update a JLabel. (Let's call this label label for now.) It does not. Is there something I am doing wrong. I have tried writing a method for the class - that declares all of the JFrame components - that changes the text of label, but when I call this method from thread2 it does not update the label. I have tried calling a super class containing thread1, but that did not seem to make a difference. Also, I have been calling the repaint() method, but that does not seem to help.

请让我知道如何从两个不同的线程更新这些JLabel.

Please let me know what I can do to update these JLabels from the two different Threads.

预先感谢， 〜雷恩

Thanks in advance, ~Rane

代码:

Class1:

JFrame frame = new JFrame();
JPanel panel = new JPanel();
JLabel label = new JLabel("V does not equal 98 Yet...");
Thread thread1 = new Thread(){

  public void run(){

    panel.add(label);
    frame.add(panel);
    System.out.println("Components added!");

  }
});

public void setLabelText(String text){
  label.setText(text);
}

Class1 = 2:

Class1=2:

v = 0;
Thread thread2 = new Thread(){

  public void run(){

    while(v < 98){

      System.out.println("V equals -" + v + "-.");
      v ++;
    }
    Class1 otherClass = new Class1();
    otherClass.label.setText("V is now equal to: " + v);
    otherClass.repaint();
    otherClass.setLabelText("V is now equal to: " + v);
    otherClass.repaint();
  }
});

推荐答案

Swing是不是线程安全的.我重复一遍:除了事件调度线程(EDT)之外，不要从任何线程调用Swing对象的任何方法. )

Swing is not thread-safe. I repeat: do not call any methods on Swing objects from any threads other than the Event Dispatch Thread (EDT)

如果要从多个不同的线程获取事件，并且希望它们直接影响Swing对象，则应使用:

If you are getting events from multiple different threads and you want to have them directly affect Swing objects, you should use:

// Note you must use final method arguments to be available inside an anonymous class
private void changeJLabel(final JLabel label, final String text) {
  EventQueue.invokeLater(new Runnable() {
    @Override
    public void run() {
      myLabel.setText(text);
    }
  });
}

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