我可以使用线程在JavaFX中设置标签文本吗?
我想在不点击任何按钮的情况下不断显示汽车的当前里程数,等等 螺纹类我可以使用线程在JavaFX中设置标签文本吗?,java,multithreading,javafx,nullpointerexception,Java,Multithreading,Javafx,Nullpointerexception,我想在不点击任何按钮的情况下不断显示汽车的当前里程数,等等 螺纹类 package threads; import javafx.fxml.FXML; import javafx.scene.control.Label; import static controller.GameWindowController.*; public class MileageThread implements Runnable { @FXML Label mileageLabel; @Override
package threads;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
import static controller.GameWindowController.*;
public class MileageThread implements Runnable {
@FXML
Label mileageLabel;
@Override
public void run() {
{
double time = 1;
while (true) {
try {
Thread.sleep(1000);
} catch (NullPointerException | InterruptedException e) {
e.printStackTrace();
}
getCar().setDistancePerSec((time * getCar().getCurrentCarSpeed()) / 3600);
getCar().setCarMileage(getCar().getCarMileage() + getCar().getDistancePerSec());
System.out.format("dziala %.3f km przebiegu %n", getCar().getCarMileage());
mileageLabel.setText(String.valueOf(getCar().getCarMileage()));
}
}
}
}
凭此记录,我收到:
Exception in thread "Thread-5" java.lang.NullPointerException
at threads.MileageThread.run(MileageThread.java:27)
这是我制作线程的课程:
package controller;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.image.ImageView;
import model.VehicleStatus;
import threads.MileageThread;
import vehicles.Car;
import java.net.URL;
import java.util.ResourceBundle;
public class GameWindowController extends Thread implements Initializable, Runnable {
@FXML
ImageView smoke;
@FXML
private Label speedLabel, mileageLabel;
static Car car;
static {
car = new Car() {
};
}
public void accelerationButtonPushed(ActionEvent event) throws InterruptedException {
car.accelerate();
speedLabel.setText(String.valueOf(car.getCurrentCarSpeed()));
smoke.setFitHeight(smoke.getX() + car.getCurrentCarSpeed());
smoke.setFitWidth(smoke.getY() + car.getCurrentCarSpeed());
System.out.println(car.getCurrentCarSpeed());
System.out.println(car.getCarMileage());
System.out.println(car.getFuel());
System.out.println(car.getStatus());
}
public void stopCarButtonPushed(ActionEvent event) throws InterruptedException {
if (car.getCurrentCarSpeed() == 0) {
System.out.println("Silnik zgasl!");
}
car.stop();
speedLabel.setText(String.valueOf(car.getCurrentCarSpeed()));
smoke.setFitHeight(smoke.getX() + car.getCurrentCarSpeed());
smoke.setFitWidth(smoke.getY() + car.getCurrentCarSpeed());
System.out.println(car.getCurrentCarSpeed());
System.out.println(car.getCarMileage());
System.out.println(car.getFuel());
System.out.println(car.getStatus());
}
public void startButtonPushed(ActionEvent event) throws InterruptedException {
if (car.getStatus() != VehicleStatus.MOVING) {
car.start();
} else System.out.println("Samochod juz jest na chodzie!");
System.out.println("Status pojazdu: " + car.getStatus());
}
@FXML
public void initialize(URL location, ResourceBundle resources) {
smoke.setFitHeight(1);
smoke.setFitWidth(1);
MileageThread mileageThread = new MileageThread();
Thread mt = new Thread(mileageThread);
mt.start();
}
public static Car getCar() {
return car;
}
}
如果你在这里发现一些基本的错误或者我误解了你,我道歉
我使用的是场景生成器,我只想使用MileageThread将文本放在其中一个标签中。如果要从JavaFX应用程序线程以外的线程修改用户界面,则必须在调用Platform.runLater时对其进行包装
只能从JavaFX应用程序线程修改JavaFX节点/控件等。如果要从JavaFX应用程序线程以外的线程修改用户界面,必须将其包装在对Platform.runLater的调用中
只能从JavaFX应用程序线程修改JavaFX节点/控件等。适合我的解决方案:
@FXML
public void initialize(URL location, ResourceBundle resources) {
PauseTransition wait = new PauseTransition(Duration.seconds(1));
wait.setOnFinished((e) -> {
mileageLabel.setText(String.valueOf(getCar().getCarMileage()));
wait.playFromStart();
});
wait.play();
}
我希望有人能帮助我:对我有效的解决方案:
@FXML
public void initialize(URL location, ResourceBundle resources) {
PauseTransition wait = new PauseTransition(Duration.seconds(1));
wait.setOnFinished((e) -> {
mileageLabel.setText(String.valueOf(getCar().getCarMileage()));
wait.playFromStart();
});
wait.play();
}
我希望有人能帮上忙:A演示这个问题也会有帮助。例如stopCarButtonPushed或Acceleration CarbuttonPushed。我在那里设置了speedLabel,它是我的速度表,但只有当按下按钮时它才会更新。我想显示波形,而无需按下按钮,例如,上面的线程,但我编写它的方式不起作用。假设适当的线程安全性,无论汽车如何更新,您可以使用定期更新标签的时间线。看,非常感谢。这篇文章帮助了我。我用了:PauseTransitionunrelated:摆脱所有这些静态…演示这个问题也会有帮助。比如在stopCarButtonPushed或accelerationCarButtonPushed中。我在那里设置了speedLabel,它是我的速度表,但只有当按下按钮时它才会更新。我想显示波形,而无需按下按钮,例如,上面的线程,但我编写它的方式不起作用。假设适当的线程安全性,无论汽车如何更新,您可以使用定期更新标签的时间线。看,非常感谢。这篇文章帮助了我。我用过:PauseTransitionunrelated:去掉所有的静态…Platform.runLater对我不起作用。我使用暂停转换。谢谢你的帮助:Platform.runLater对我不起作用。我使用暂停转换。谢谢你的帮助: