JavaFX 简单更新标签(线程)

Question

我试图向一些初学者演示如何在JavaFX应用程序上设置标签以自动更新。基本上，他们希望标签上的值每分钟左右减少一次，而无需任何用户交互。

Java不是我的强项，通过之前的一些问题，我得到我需要处理线程和Runnable((。

我已经将下面的代码放在一起，但我只是想知道是否有更好的方法来做到这一点，或者更简单的方法来用更简单的代码演示相同的结果。

public class MainTimer2 extends Application {
private int count = 100;
private Label response = new Label(Integer.toString(count));
public static void main(String[] args) {
launch(args);
}
//Update function
private void decrementCount() {
count--;
response.setText(Integer.toString(count));
}
@Override
public void start(Stage myStage) {
myStage.setTitle("Update Demo");
//Vertical and horizontal gaps set to 10px
FlowPane rootNode = new FlowPane(10, 10);
rootNode.setAlignment(Pos.CENTER);
Scene myScene = new Scene(rootNode, 200, 100);
myStage.setScene(myScene);
Thread thread = new Thread(new Runnable() {
@Override
public void run() {
Runnable updater = new Runnable() {
@Override
public void run() {
decrementCount();
}
};
while (true) {
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
System.out.println("Timer error");
}
// UI update is run on the Application thread
Platform.runLater(updater);
}
}
});
// don't let thread prevent JVM shutdown
thread.setDaemon(true);
thread.start();
rootNode.getChildren().addAll(response);
myStage.show();
}
}

Answer 1

使用 PauseTransition 倒计时：

import javafx.animation.PauseTransition;
import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.FlowPane;
import javafx.stage.Stage;
import javafx.util.Duration;
public class MainTimer2 extends Application {
private int count = 100;
private Label response = new Label(Integer.toString(count));
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage myStage) {
myStage.setTitle("Update Demo");
//Vertical and horizontal gaps set to 10px
FlowPane rootNode = new FlowPane(10, 10);
rootNode.setAlignment(Pos.CENTER);
Scene myScene = new Scene(rootNode, 200, 100);
myStage.setScene(myScene);
rootNode.getChildren().addAll(response);
myStage.show();
update();
}
private void update() {
PauseTransition pause = new PauseTransition(Duration.seconds(1));
pause.setOnFinished(event ->{
decrementCount();
pause.play();
});
pause.play();
}
//Update function
private void decrementCount() {
count = (count > 0) ? count -1 : 100;
response.setText(Integer.toString(count));
}
}

或者，您可以使用时间轴：

private void update() {
KeyFrame keyFrame = new KeyFrame(
Duration.seconds(1),
event -> {
decrementCount();
}
);
Timeline timeline = new Timeline();
timeline.setCycleCount(Animation.INDEFINITE);
//if you want to limit the number of cycles use 
//timeline.setCycleCount(100);
timeline.getKeyFrames().add(keyFrame);
timeline.play();
}