检查线程是否需要 EDT？

发布于 2024-08-29 21:23:21 字数 607 浏览 12 评论 0原文

我有一个用 Swing 实现的 UI。一个组件执行一些可能需要一些时间的工作，因此我使用 SwingUtilities.invokeLater。然而，我正在阅读一些旧代码，并在 ActionListener 中发现了这一点：

if (!SwingUtilities.isEventDispatchThread()) {
    SwingUtilities.invokeLater(new Runnable() {
         public void run() {
             // code X
         }
    });
} else {
   // code X
}

我认为这是有道理的，因为它将 code X 与 EDT 分开。然而，我发现它很容易出错，因为我已经使用过它几次了，而且两次我都忘记了 else 部分。

问题是：SwingUtilities.isEventDispatchThread() 检查是否必要？或者我可以~~假设我不在 EDT 中并且~~始终使用invokeLater吗？

多谢。

原文

I have an UI implemented with Swing. One component does some work that may take some time, so I use SwingUtilities.invokeLater. However, I was reading some old code and found this in an ActionListener:

if (!SwingUtilities.isEventDispatchThread()) {
    SwingUtilities.invokeLater(new Runnable() {
         public void run() {
             // code X
         }
    });
} else {
   // code X
}

I thought that it made sense since it separates code X from the EDT. However, I found it error-prone since I have used it a couple of times and both times I forgot the else part.

The question is: is the SwingUtilities.isEventDispatchThread() checking necessary? Or could I ~~assume that I am not in the EDT and~~ always use invokeLater?

Thanks a lot.

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想你的星星会说话 2024-09-05 21:23:21

即使您在 EDT 上，稍后调用也可以，但是它肯定会改变事件的时间，因此您必须确保在 EDT 上时不依赖于此处的代码顺序。话虽这么说，避免忘记 else 的一个简单方法是将调用包装在实用方法中：

public static void invokeInDispatchThreadIfNeeded(Runnable runnable) {
    if (EventQueue.isDispatchThread()) {
        runnable.run();
    } else {
        SwingUtilities.invokeLater(runnable);
    }
}

这样您就永远不会忘记 else。

另外，一般来说，在您的 idom 中重复 code x 是一个非常糟糕的主意，因为您稍后可能会发现您必须修复或改进该代码，并且您只会在一个地方执行此操作，从而留下错误在另一个。

Invoking later is fine even if you are on the EDT, however it certainly changes the timing of events, so you have to be sure that you were not dependent on the sequence of the code here when you were on the EDT. That being said, a simple way to avoid forgetting the else is to wrap the call in a utility method:

public static void invokeInDispatchThreadIfNeeded(Runnable runnable) {
    if (EventQueue.isDispatchThread()) {
        runnable.run();
    } else {
        SwingUtilities.invokeLater(runnable);
    }
}

That way you never forget the else.

Also, in general in your idom repeating code x is a very bad idea, as you may find later that you have to fix or improve that code and you will only do it in one place, leaving a bug in the other.

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