How to get java wait for javascript?

Question

I try to route on TomTom maps and get a callback from the routing method. So I made up a Java Application in JavaFx and showed the TomTom Map on my webview from JavaFX.

Now my issue: I do call a method in Javascript from JavaCode and want to get the response from the routing method, but this takes time and is asynchronous. And I just get the Promise Object from javascript and not the response...

I changed the javscript functions and don't work with promises anymore.

Edited Code:

JavaCode:

package application;

import java.io.BufferedInputStream;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.time.LocalDate;
import java.time.LocalTime;
import java.util.Properties;

import javafx.application.Application;
import javafx.concurrent.Worker.State;
import javafx.scene.Scene;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import netscape.javascript.JSObject;

public class Main extends Application{

static JSObject window;
static Stage primaryStage;

public void start(Stage primaryStage) {



try {
        Browser browser = new Browser();
        browser.getWebEngine().getLoadWorker().stateProperty()
        .addListener((obs, oldValue, newValue) -> {
            if (newValue == State.SUCCEEDED) {

                window = (JSObject) browser.getWebEngine().executeScript("window");

                System.out.println("Now call gogo");
                System.out.println("gogo Output: " + window.call("gogo"));

                WebController webControl= new WebController(browser, window);
                window.setMember("clickController", webControl);

                System.out.println("First it will go over here and print this");

                LocalDate date = LocalDate.now();
                try {
                    FileWriter fw = new FileWriter("output/"+date+".csv", true);
                    BufferedWriter bw = new BufferedWriter(fw);
                    bw.append(LocalTime.now() + ";" + delay + "\n");
                    bw.close();
                    fw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
        Scene scene = new Scene(browser, Color.web("#666970"));
        primaryStage.setTitle("TestApplication");
        primaryStage.setScene(scene);
        primaryStage.show();
    } catch(Exception e) {
        e.printStackTrace();
    }
}

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

Javascript:

    function gogo(){
    var data = goTask(function(data) {
    console.log(data.summary.totalDistanceMeters);
    clickController.print("after all that java stuff it will invoke this syso")
    clickController.print("output Routing function: " + data.summary.totalDistanceMeters);
    clickController.print("gogo output with invoking java from javascript");    
    return data;
    });
    return data;
    }

    function goTask(call){
    function callback(d){
        call(d);
    }
    routeMe(callback);
    function routeMe(callbackFunc){
        var points = [ [48.7061643,9.1664228], [48.7322085,9.0489835] ]; 
        var service = new tomtom.services.RoutingService("'ApiKey'");
        var options = {
            includeTraffic: true
            // avoidTolls: true
        };
        service.getRoute(points, options,callbackFunc);
    }
    }

Output:

Now call gogo
gogo Output: undefined
First it will go over here and print this syso
WebController Syso: after all that java stuff it will invoke this
WebController Syso: output Routing function: 9419
WebController Syso: gogo output with invoking java from javascript

The problem is that Java does not wait on Javascript...

Can anyone help me?

Edit:

@Bonatti I am running it on

ScriptEngineFactory getEngine --> Oracle Nashorn

ScriptEngine getLanguage --> ECMAScript

Answer 1

I do not know the tomtom service. But from reading your code return new Promise is working as intended, as you are receiving the Promise I would suggest having another function to receive the route then use a SOAP to read the data into your application

Answer 2

Right now you are returning a Promise to Java, which doesn't know what to do with it. It won't wait for the promise to be fulfilled, and since there's no way of it interpreting the promise not much happens.

You can only handle this promise within Javascript, with something like .then( ... ), wherein you actually handle the result you expect right now (the delay).

Forcing the promise to be used synchronously will not work, it would be the same issue if you would want to handle your function result synchronously within Javascript (Call An Asynchronous Javascript Function Synchronously).

Try @Evan Knowles' answer here but with your callback instead:

We're going to set a listener for the successful state - basically we're going to inject a Java class into the JavaScript and have it call us back. Let's create a WebController that checks what is passed in and prints out the ID

How to catch return value from javascript in javafx?