方法中的java更新JavaFX阶段

Question

我正在写一个程序，它使用大量的数据来做一些计算，并且需要相当长的时间才能完成。这就是为什么我想更新并通知用户当前正在完成的程序的百分比。但是，我不知道如何在计算方法中更新阶段

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Pane;
import javafx.scene.layout.VBox;
import javafx.scene.text.Text;
import javafx.stage.Stage;
 
public class Main extends Application {
    
    public void calculate() {
        //Here I want to change the "percentage text"
        //and update the stage.
    }
    
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Hello World!");
        
        Text percentage = new Text();
        
        Button btn = new Button();
        btn.setText("Say 'Hello World'");
        btn.setOnAction(new EventHandler<ActionEvent>() {
 
            @Override
            public void handle(ActionEvent event) {
                calculate();
            }
        });
        
        final GridPane inputGridPane = new GridPane();
        GridPane.setConstraints(btn, 0, 0);
        GridPane.setConstraints(percentage, 1, 0);
        inputGridPane.setHgap(6);
        inputGridPane.setVgap(6);
        inputGridPane.getChildren().addAll(btn, percentage);
        
        final Pane rootGroup = new VBox(12);
        rootGroup.setPrefWidth(400);
        rootGroup.setPrefHeight(225);
        rootGroup.getChildren().addAll(inputGridPane);
        rootGroup.setPadding(new Insets(12,12,12,12));
        
        primaryStage.setScene(new Scene(rootGroup));
        primaryStage.show();
    }
    
    public static void main(String[] args) {
        launch(args);
    }
}

这就是我的代码大致的样子。先谢谢你

Answer 1

JavaFx提供了一个名为“Task”的类，它可以用于后台计算，同时保持进程同步

我建议这样做：

创建用于执行繁重计算的第二个类扩展任务：

import javafx.concurrent.Task;

public class CalculationTask extends Task<String> {
    @Override
    protected String call() throws Exception {
        for (int i = 0; i < 100000000;i++) {
            updateProgress(i, 100000000);
        }

        succeeded();
        return "This is the computed result... Datatype can be changed by generics if you are calculation numbers";
    }
}

这是在应用程序类中使用它的一种方法：

import javafx.application.Application;
import javafx.concurrent.Task;
import javafx.concurrent.WorkerStateEvent;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.Dialog;
import javafx.scene.control.ProgressBar;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Pane;
import javafx.scene.layout.VBox;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Hello World!");



        Button btn = new Button();
        btn.setText("Say 'Hello World'");

        Task<String> calculationTask = new CalculationTask();

        ProgressBar progressBar = new ProgressBar(); //ProgressIndicator could also be used
        progressBar.progressProperty().bind(calculationTask.progressProperty());
        progressBar.visibleProperty().bind(calculationTask.runningProperty());

        btn.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent event) {
                calculationTask.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
                    @Override
                    public void handle(WorkerStateEvent workerStateEvent) {
                        new Alert(Alert.AlertType.CONFIRMATION, calculationTask.getValue()).show();
                    }
                });
                new Thread(calculationTask).start();
            }
        });




        final GridPane inputGridPane = new GridPane();
        GridPane.setConstraints(btn, 0, 0);
        GridPane.setConstraints(progressBar, 1, 0);
        inputGridPane.setHgap(6);
        inputGridPane.setVgap(6);
        inputGridPane.getChildren().addAll(btn, progressBar);

        final Pane rootGroup = new VBox(12);
        rootGroup.setPrefWidth(400);
        rootGroup.setPrefHeight(225);
        rootGroup.getChildren().addAll(inputGridPane);
        rootGroup.setPadding(new Insets(12,12,12,12));

        primaryStage.setScene(new Scene(rootGroup));
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

我希望这有帮助，否则请随意提问