New Thread doesn't open scene

Question

I'm here for the third time, this time about the threading within JavaFX.

So, I'm trying to have a loading screen, and the loadingscreen has a controller which is used as interface (NOT ACTUAL INTERFACE) between the entry and the result.

Here is the code:

private void createLoadingScreenScene(String id) throws Exception {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("/com/lollookup/scene/loadingscreen/loadingscreen.fxml"));
        Stage stage = new Stage(StageStyle.DECORATED);
        stage.setScene(new Scene(loader.load()));
        stage.show();
        Task task = new Task<Void>() {
            @Override
            protected Void call() throws Exception {
                LoadingScreenController controller = loader.getController();
                controller.setSummoner(lookupTextField.getText(), regionsBox.getSelectionModel().getSelectedItem());
                switch (id.toLowerCase()) {
                    case "ag_lookup":
                        controller.loadActiveGame();
                        break;
                    case "sum_lookup":
                        controller.loadProfile();
                        break;
                }
                return null;
            }
        };
        ExecutorService executorService = Executors.newSingleThreadExecutor();
        Future<?> submit = executorService.submit(task);
    }

everything works perfectly fine until this: assuming the id is sum_lookup this method gets executed:

public void loadProfile() {
        if (summoner != null) {
            try {
                System.out.println("Loading profile scene");
                createProfileScene();
            } catch (DataException | WrongRequestFormatException | ReplyException | IOException e) {
                e.printStackTrace();
            }
        }
    }

And createProfileScene is the following:

private void createProfileScene() throws IOException, DataException, WrongRequestFormatException, ReplyException {
    System.out.println("Going ham..");
    String summonerName = summoner.getName();
    System.out.println("Going ham..0.5");
    FXMLLoader loader = new FXMLLoader(getClass().getResource("/com/lollookup/scene/summonerlookup/profile.fxml"));
    System.out.println("Going ham.. 0.8");
    Stage stage = new Stage(StageStyle.DECORATED);
    System.out.println("Going ham..1");
    stage.setScene(new Scene(loader.load()));
    ProfileController controller = loader.getController();
    List<ChampionMastery> championMasteries = leagueAPI.getChampionMasteries(summoner.getId()); //TODO here
    System.out.println("Going ham..2");
    stage.show()

Now everything works until "Going ham 0.8" is being printed. The program literally stops outputting data.

That's the output:

Loading profile scene
Going ham..
Going ham..0.5
Going ham.. 0.8

What am i doing wrong?

EDIT:

Thats the code I now changed: private void createLoadingScreenScene(String id) throws Exception { FXMLLoader loader = new FXMLLoader(getClass().getResource("/com/lollookup/scene/loadingscreen/loadingscreen.fxml")); Stage stage = new Stage(StageStyle.DECORATED); stage.setScene(new Scene(loader.load())); LoadingScreenController controller = loader.getController(); controller.setSummoner(lookupTextField.getText(), regionsBox.getSelectionModel().getSelectedItem()); switch (id.toLowerCase()) { case "ag_lookup": controller.loadActiveGame();

        case "sum_lookup":
            controller.loadProfile();

    }
    stage.show();
}

This is the actual task which takes heavy load of time: (now in a Task)

Task task = new Task<Void>() {
        @Override
        protected Void call() throws Exception {
            System.out.println("Going ham..");
            String summonerName = summoner.getName();
            System.out.println("Going ham..0.5");
            FXMLLoader loader = new FXMLLoader(getClass().getResource("/com/lollookup/scene/summonerlookup/profile.fxml"));
            System.out.println("Going ham.. 0.8");
            Stage stage = new Stage(StageStyle.DECORATED);
            System.out.println("Going ham..1");
            stage.setScene(new Scene(loader.load()));
            ProfileController controller = loader.getController();
            List<ChampionMastery> championMasteries = leagueAPI.getChampionMasteries(summoner.getId()); //TODO unused
            System.out.println("Going ham..2");
            ChampionInfoData[] championStatsSummary = leagueAPI.getChampionStatsRanked(summoner.getId(), Season.SEASON_7).getChampionStatsSummary().stream().filter(element -> element.getId() != 0).map(element -> {
                try {
                    ChampionStats championStats = element.getChampionStats();
                    int championId = element.getId();
                    return new ChampionInfoData(leagueAPI.getImageUrl(championId), leagueAPI.getChampionData(championId).getName(), championStats.displayAverageKDA(), championStats.displayWinrate(), championStats.displayAverageCreepScore(), "0");
                } catch (ReplyException | DataException | IOException | WrongRequestFormatException e) {
                    e.printStackTrace();
                }
                return null;
            }).toArray(ChampionInfoData[]::new);
            System.out.println("Did i come this far? Yes!" + championStatsSummary.length);
            controller.createProfile(new SummonerData("http://avatar.leagueoflegends.com/" + summoner.getRegion().getShortCode() + "/" + summonerName.replace(" ", "") + ".png", summonerName, String.valueOf(summoner.getSummonerLevel())), championStatsSummary);
            stage.show();
            return null;
        }
    };
    ExecutorService executorService = Executors.newSingleThreadExecutor();
    executorService.submit(task);

Yet the output still is:

Loading profile scene
Going ham..
Going ham..0.5
Going ham.. 0.8