javaFX 在窗口的标题栏显示当前时间，1秒更新一次时间

 例1：在窗口的标题栏显示当前时间，1秒更新一次时间

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import javafx.util.Duration;

public class Main extends Application {

    public static void main(String[] args) {
        launch(args);
    }
    
    @Override
    public void start(Stage primaryStage) throws Exception {
        // Create a pane to hold two players
        GridPane pane = new GridPane();
        pane.setStyle("-fx-border-color: green;");
        pane.setPadding(new Insets(10, 10, 10, 10));
        pane.setHgap(10);
        pane.setVgap(10);
        
        // Date format
        DateFormat df = new SimpleDateFormat("yyyy.MM.dd hh:mm:ss");
        
        EventHandler<ActionEvent> eventHandler = e -> {
            primaryStage.setTitle(df.format(new Date()));
            System.out.println(df.format(new Date()));
        };
        
        Timeline animation = new Timeline(new KeyFrame(Duration.millis(1000), eventHandler));
        animation.setCycleCount(Timeline.INDEFINITE);
        animation.play();
        
        // Create a scene
        Scene scene = new Scene(pane, 400, 200);
        primaryStage.setScene(scene);
        primaryStage.setTitle("Starting");
        primaryStage.setResizable(false);
        primaryStage.show();
    }
}

运行效果：

关于lambda表达式：https://www.cnblogs.com/franson-2016/p/5593080.html

例1中的第34~37行的代码是lambda表达式的写法（感觉lambda表达式好难理解）。在这里，其实就是将一个匿名内部类的引用赋给一个变量。

EventHandler<ActionEvent> eventHandler = e -> {
    primaryStage.setTitle(df.format(new Date()));
    System.out.println(df.format(new Date()));
};

以上代码等同于：

EventHandler<ActionEvent> eventHandler = new EventHandler<ActionEvent>() {
    @Override
    public void handle(ActionEvent event) {
        primaryStage.setTitle(df.format(new Date()));
        System.out.println(df.format(new Date()));
    }
};

例1中的第34~39行的代码可以改写成：

Timeline animation = new Timeline(new KeyFrame(Duration.millis(1000), new EventHandler<ActionEvent>() {
    @Override
    public void handle(ActionEvent event) {
        primaryStage.setTitle(df.format(new Date()));
        System.out.println(df.format(new Date()));
    }
}));