SwingUtilities.invokeLater
我的问题与 SwingUtilities.invokeLater 有关。我应该什么时候使用它？每次需要更新 GUI 组件时都必须使用吗？它到底有什么作用？是否有替代方案，因为它听起来不直观并且添加了看似不必要的代码？
My question is related to SwingUtilities.invokeLater. When should I use it? Do I have to use each time I need to update the GUI components? What does it exactly do? Is there an alternative to it since it doesn't sound intuitive and adds seemingly unnecessary code?
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不，如果您已经处于事件调度线程 (EDT) 上，情况总是如此，则不需要响应用户发起的事件（例如单击和选择）时。 （
actionPerformed方法等始终由 EDT 调用。）如果您不在 EDT 上并且想要进行 GUI 更新（如果您想更新来自某个计时器线程或某个网络线程等的 GUI），您必须安排由 EDT 执行的更新。这就是这个方法的用途。
Swing 基本上是线程不安全的。即，与该 API 的所有交互都需要在单个线程（EDT）上执行。如果您需要从另一个线程（计时器线程、网络线程等）进行 GUI 更新，您需要使用您提到的方法（SwingUtilities.invokeLater、SwingUtilities.invokeAndWait，...）。
No, not if you're already on the event dispatch thread (EDT) which is always the case when responding to user initiated events such as clicks and selections. (The
actionPerformedmethods etc, are always called by the EDT.)If you're not on the EDT however and want to do GUI updates (if you want to update the GUI from some timer thread, or from some network thread etc), you'll have to schedule the update to be performed by the EDT. That's what this method is for.
Swing is basically thread unsafe. I.e., all interaction with that API needs to be performed on a single thread (the EDT). If you need to do GUI updates from another thread (timer thread, networking thread, ...) you need to use methods such as the one you mentioned (SwingUtilities.invokeLater, SwingUtilities.invokeAndWait, ...).
invokeLater()的基本用法主方法应始终包含在
invokeLater()延迟（但异步）操作/事件到
EventQueue的末尾，如果 EDT 不存在，则必须使用
invokeLater()创建一个新的 EDT。您可以使用if (SwingUtilities.isEventDispatchThread()) {...进行测试。
if (SwingUtilities.isEventDispatchThread()) {...存在
invokeAndWait()，但直到今天我（只是我的观点）可以找不到使用invokeAndWait()而不是invokeLater()的原因，除了对 GUI（JTree 和 JTable）进行硬更改，但只是使用Substance L&F（非常适合测试 EDT 上事件的一致性）基本内容：Swing 中的并发
后台任务的所有输出都必须包装在
invokeLater()Basic usage for
invokeLater()Main methods should be always wrapped in
invokeLater()Delayed (but asynchronously) action/event to the end of
EventQueue,If EDT doesn't exists then you have to create a new EDT by using
invokeLater(). You can test it withif (SwingUtilities.isEventDispatchThread()) {...There exists
invokeAndWait(), but till today I (just my view) can't find a reason for usinginvokeAndWait()instead ofinvokeLater(), except hard changes into GUI (JTree & JTable), but just with Substance L&F (excellent for testing consistency of events on the EDT)Basic stuff: Concurrency in Swing
All output from background tasks must be wrapped in
invokeLater()每个 Swing 应用程序至少有 2 个线程：
如果您想更新 UI，您应该在 EDT 中执行代码。
SwingUtilities.invokeLater、SwingUtilities.invokeAndWait、EventQueue.invokeLater、EventQueue.invokeAndWait 等方法允许您通过 EDT 执行代码。
Every Swing application has at least 2 threads:
If you want to update the UI you should execute code within the EDT.
Methods like SwingUtilities.invokeLater, SwingUtilities.invokeAndWait, EventQueue.invokeLater, EventQueue.invokeAndWait allow you to execute code by the EDT.
理解的关键是 Java 有一个单独的线程 (EDT) 处理 Swing 相关事件。
您应该使用
invokeLater()来显示桌面应用程序的主JFrame（例如），而不是尝试在当前线程中执行此操作。它还将为稍后正常关闭应用程序创建上下文。对于大多数应用程序来说就是这样。
不会。如果您修改 GUI 组件，它将触发一个事件，该事件会注册以供 Swing 稍后调度。如果有此事件的侦听器，EDT 线程将在以后的某个地方调用它。您不需要使用
invokeLater()，只需在组件上正确设置侦听器即可。请记住，该线程与屏幕上绘制框架等的线程相同。因此，侦听器不应执行复杂/长时间/CPU 密集型任务，否则您的屏幕将冻结。
除了在组件上使用
invokeLater()+ 您感兴趣的侦听器显示应用程序之外，您不需要编写更多代码。其余的由 Swing 处理。What is key to understand is that Java has a separate thread (EDT) handling Swing related events.
You should use
invokeLater()to display the mainJFrameof a desktop application (for example), instead of trying to do it in the current thread. It will also create the context for graceful closing of the application later.That's about it for most applications.
No. If you modify a GUI component, it will trigger an event which is registered for later dispatching by Swing. If there is a listener for this event, the EDT thread will call it somewhere down the road. You don't need to use
invokeLater(), just set your listeners on components properly.Keep in mind that this thread is the same thread drawing frames etc... on your screen. Hence, listeners should not perform complex/long/CPU intensive tasks, otherwise your screen will freeze.
You don't need to write more code than displaying your application with
invokeLater()+ listeners you are interested in on component. The rest is handled by Swing.大多数用户启动的事件（点击、键盘）已经在 EDT 上，因此您不必为此使用 SwingUtilities。这涵盖了很多情况，除了更新 EDT 的 main() 线程和工作线程。
Most user-initiated events (clicks, keyboard) will already be on the EDT so you won't have to use SwingUtilities for that. That covers a lot of cases, except for your main() thread and worker threads that update the EDT.