java - Java 中的主线程与 UI 线程

Question

在此处作为答案给出的许多 Swing 片段中，有一个对 SwingUtilities#invokeLater 的调用来自 main 方法:

public class MyOneClassUiApp {

    private constructUi() {
        // Some Ui related Code
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new MyOneClassUiApp().constructUi();
            }
        });
    }
}

但是根据Threads and Swing article ，从主线程构建 UI 是安全的:

A few methods are thread-safe: In the Swing API documentation, thread-safe methods are marked with this text:

This method is thread safe, although most Swing methods are not.

An application's GUI can often be constructed and shown in the main thread: The following typical code is safe, as long as no components (Swing or otherwise) have been realized:

public class MyApplication {
public static void main(String[] args) {
   JFrame f = new JFrame("Labels");
   // Add components to 
   // the frame here... 
   f.pack(); 
   f.show(); 
   // Don't do any more GUI work here... 
   } 
}

那么，是否有真正的(线程安全)理由通过SwingUtilities#invokeLater在main中构建UI ，或者这只是一种习惯，记得在其他情况下这样做吗？

Answer 1

“Swing 单线程规则:Swing 组件和模型应该仅从事件调度线程创建、修改和查询。”— Java Concurrency in Practice , 还讨论了 here和 here .如果您不遵守此规则，那么您将无法可靠地构建、修改或查询可能假设您确实遵守此规则的任何组件或模型。一个程序可能看起来工作正常，但在不同的环境中却神秘地失败了。由于违规行为可能不明显，请使用提到的方法之一验证正确使用 here .