例1：在窗口的标题栏显示当前时间，1秒更新一次时间

1 import java.text.DateFormat; 2 import java.text.SimpleDateFormat; 3 import java.util.Date; 4  5 import javafx.animation.KeyFrame; 6 import javafx.animation.Timeline; 7 import javafx.application.Application; 8 import javafx.event.ActionEvent; 9 import javafx.event.EventHandler;10 import javafx.geometry.Insets;11 import javafx.scene.Scene;12 import javafx.scene.layout.GridPane;13 import javafx.stage.Stage;14 import javafx.util.Duration;15 16 public class Main extends Application {17 18     public static void main(String[] args) {19         launch(args);20     }21     22     @Override23     public void start(Stage primaryStage) throws Exception {24         // Create a pane to hold two players25         GridPane pane = new GridPane();26         pane.setStyle("-fx-border-color: green;");27         pane.setPadding(new Insets(10, 10, 10, 10));28         pane.setHgap(10);29         pane.setVgap(10);30         31         // Date format32         DateFormat df = new SimpleDateFormat("yyyy.MM.dd hh:mm:ss");33         34         EventHandler
     
       eventHandler = e -> {35             primaryStage.setTitle(df.format(new Date()));36             System.out.println(df.format(new Date()));37         };38         39         Timeline animation = new Timeline(new KeyFrame(Duration.millis(1000), eventHandler));40         animation.setCycleCount(Timeline.INDEFINITE);41         animation.play();42         43         // Create a scene44         Scene scene = new Scene(pane, 400, 200);45         primaryStage.setScene(scene);46         primaryStage.setTitle("Starting");47         primaryStage.setResizable(false);48         primaryStage.show();49     }50 }
     

运行效果：

 

 

关于lambda表达式：

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

以上代码等同于：

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