我刚刚在javafx中了解到一些新闻,然后我想应用它们,所以我选择做一个计数器;但是当我在标签上设置文本时,它不会改变;我用 System.out.print 测试了它,效果很好。 这是我的代码:
public class Controller {
@FXML
private Label time;
@FXML
private Button start;
public void Counter(ActionEvent event)
{
start.setText("hello");
time.setText("00 : 00 : 00");
int h=0,m=0,s=0,i=0;
while(true)
{
try {
s++;
if(s==60) {s=0;m++;}
if(m==60) {m=0;h++;}
System.out.println(Integer.toString(h)+" : "+String.valueOf(m)+" : "+String.valueOf(s));
time.setText(Integer.toString(h)+" : "+String.valueOf(m)+" : "+String.valueOf(s));
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
感谢您的帮助! ;)
最佳答案
这里重要的是,您需要了解对 UI 进行的任何更新都需要在 UI 主线程内完成。您还应该避免阻塞 UI 的主线程,这将阻止 UI 更新。
首先,请通读 Concurrency in JavaFX
当您处理时间或持续时间时,您应该始终使用专用库,例如 java.time
。为什么?因为实际上一天并没有 24 小时,一分钟也没有 60 秒 - 我知道,这很奇怪不是吗。
你可以...
使用时间轴
import java.time.LocalDateTime;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Duration;
public class Test extends Application {
private LocalDateTime startTime;
private Timeline timer;
private Label time;
@Override
public void start(Stage primaryStage) {
time = new Label("...");
Button btn = new Button();
btn.setText("Start");
btn.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
if (timer != null) {
timer.stop();
}
startTime = LocalDateTime.now();
timer = new Timeline(new KeyFrame(Duration.millis(500), new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
LocalDateTime now = LocalDateTime.now();
java.time.Duration duration = java.time.Duration.between(startTime, now);
time.setText(format(duration));
}
}));
timer.setCycleCount(Timeline.INDEFINITE);
timer.play();
}
});
VBox root = new VBox();
root.setAlignment(Pos.CENTER);
root.getChildren().add(time);
root.getChildren().add(btn);
Scene scene = new Scene(root, 300, 250);
primaryStage.setTitle("Hello World!");
primaryStage.setScene(scene);
primaryStage.show();
}
protected String format(java.time.Duration duration) {
long hours = duration.toHours();
long mins = duration.minusHours(hours).toMinutes();
long seconds = duration.minusMinutes(mins).toMillis() / 1000;
return String.format("%02dh %02dm %02ds", hours, mins, seconds);
}
public static void main(String[] args) {
launch(args);
}
}
使用AnimationTimer
这可能是首选解决方案,因为计时器的调用与动画引擎的帧刷新同步
import java.time.LocalDateTime;
import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class Test extends Application {
private LocalDateTime startTime;
private AnimationTimer timer;
private Label time;
@Override
public void start(Stage primaryStage) {
time = new Label("...");
Button btn = new Button();
btn.setText("Start");
btn.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
if (timer != null) {
timer.stop();
}
startTime = LocalDateTime.now();
timer = new AnimationTimer() {
@Override
public void handle(long click) {
LocalDateTime now = LocalDateTime.now();
java.time.Duration duration = java.time.Duration.between(startTime, now);
time.setText(format(duration));
}
};
timer.start();
}
});
VBox root = new VBox();
root.setAlignment(Pos.CENTER);
root.getChildren().add(time);
root.getChildren().add(btn);
Scene scene = new Scene(root, 300, 250);
primaryStage.setTitle("Hello World!");
primaryStage.setScene(scene);
primaryStage.show();
}
protected String format(java.time.Duration duration) {
long hours = duration.toHours();
long mins = duration.minusHours(hours).toMinutes();
long seconds = duration.minusMinutes(mins).toMillis() / 1000;
return String.format("%02dh %02dm %02ds", hours, mins, seconds);
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
}
关于java - setTitle() 和 Thread.sleep(),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49583385/