Live-Update LineChart in JavaFX

问题

I have problem with updating JavaFX UI - I want to update line chart and some labels on my scene when it's already shown. My task is to do some calculations (calling function in other class which returns dataseries) and add updated series to the chart.

The following code (which is in a loop) may present what i want to do:

//double x - x value of the point i want to add to my chart
//double y - y value of the point i want to add to my chart
//string s  - some result from function
mySeries.getData().add(new XYChart.Data(x, y));
someLabel.setText(s);

My program freezes and give only final solution after some time, but i want to see the points on the chart exactly after they're added, not at the end of the execution. If the process is too quick, i would like to add Thread.sleep(1000) before adding the next point to the chart.

I know it has something to do with threads, concurrency and tasks, but i wasn't able to find a solution yet. I tried to use some code I found here but still I don't know the correct answer.

回答1:

Every user action, e.g. click a button, will notify your action listener within the UI thread. Logic in the UI thread should be as fast as possible. I think you are reacting on a user event and then execute a long running task in the UI thread. Try to put your code in a background thread. Further you need to put the UI updates back again in the UI thread. You can do this with "Platform.runLater(...)".

Something like this:

public class Test extends Application {

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

    @Override
    public void start(Stage primaryStage) throws Exception {
        Scene scene = new Scene(createChart());
        primaryStage.setScene(scene);
        primaryStage.setHeight(800);
        primaryStage.setWidth(1200);
        primaryStage.show();
    }

    private Parent createChart() {
        LineChart<Number, Number> lc = new LineChart<>(new NumberAxis(), new NumberAxis());
        XYChart.Series<Number, Number> series = new XYChart.Series<>();
        lc.getData().add(series);

        new Thread(() -> {
            try {
                Thread.sleep(5000);
                for (int i = 0; i < 15; i++) {
                    int finalI = i;
                    Platform.runLater(() -> series.getData().add(new XYChart.Data<>(1 + finalI, 1 + finalI)));
                    Thread.sleep(1000);
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();

        return lc;
    }

}

来源：https://stackoverflow.com/questions/44036735/live-update-linechart-in-javafx

标签

java

multithreading

javafx

concurrency

linechart