Platform.runLater问题 - 延迟执行 [英] Platform.runLater Issue - Delay Execution

问题描述

Button button = new Button("Show Text");
button.setOnAction(new EventHandler<ActionEvent>(){
    @Override
    public void handle(ActionEvent event) {
        Platform.runLater(new Runnable(){
            @Override
            public void run() {
                field.setText("START");
            }
       });

        try {
            Thread.sleep(5000);
        } catch (InterruptedException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }

        Platform.runLater(new Runnable(){
            @Override
            public void run() {
                field.setText("END");
            }
        });
        }
});

运行上面的代码后， field.setText（START）未执行，我的意思是textfield没有将其文本设置为START，为什么？如何解决此问题？

After running the code above, field.setText("START") is not executed, I mean textfield did not set its text to "START", WHY? How to resolve this?

推荐答案

请记住，在JavaFX线程上调用按钮的 onAction ，因此您实际上会停止UI线程5秒钟。当UI线程在这五秒结束时被解冻时，两个更改都会连续应用，因此您最终只能看到第二个。

Keep in mind that the button's onAction is called on the JavaFX thread, therefore you are effectively halting your UI thread for 5 seconds. When the UI thread is un-frozen at the end of these five seconds both changes are applied successively, so you end up only seeing the second.

你可以通过在新线程中运行上面的所有代码来解决这个问题：

You can fix this by running all code above in a new thread:

    Button button = new Button();
    button.setOnAction(event -> {
        Thread t = new Thread(() -> {
            Platform.runLater(() -> field.setText("START"));
            try {
                Thread.sleep(5000);
            } catch (InterruptedException ex) {
                Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
            }
            Platform.runLater(() -> field.setText("END"));
        });

        t.start();
    });

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