JavaFX pass data to jfxtras gauge from Arduino

Question

First let me thank you for any guidance you might be able to provide on this. I have been racking my brains to get this to work, and have been looking at many threads here, with no luck. I am new to Java and JavaFX, but have a C# background, primarily on MSFT visual Studio. I am currently using IntelliJ as my IDE platform.

What I am trying to do is (I thought) simple enough: I am reading and successfully parsing data coming in from an Arduino controller, which is reading a sensor, that provides readings for a power meter. I have my data in a comma delimited form, and with a buffered reader and serial port event, I am able to parse a line, string.split it, and then place in into an array (after transforming to Double). This part works well, and as you can see from the code, I am also printing this to the console with no issues:

package sample;

import eu.hansolo.enzo.gauge.RectangularGauge;
import gnu.io.*;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.fxml.FXML;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;

import java.io.*;

public class Main extends Application implements SerialPortEventListener {
SerialPort serialPort = null;
private BufferedReader serialIn;
private OutputStream serialOut;
public Double power;


@FXML
private RectangularGauge fwdpower;


@Override
public void start(Stage primaryStage) throws Exception {
    Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
    primaryStage.setTitle("Power Meter");
    primaryStage.setScene(new Scene(root, 380, 320));
    primaryStage.show();

    //
    CommPortIdentifier port = CommPortIdentifier.getPortIdentifier("COM60");
    CommPort commPort = port.open(this.getClass().getName(), 2000);
    serialPort = (SerialPort) commPort;
    serialPort.setSerialPortParams(115200, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
    serialIn = new BufferedReader(new InputStreamReader((serialPort.getInputStream())));
    serialPort.addEventListener(this);
    serialPort.notifyOnDataAvailable(true);
    //
}


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

@Override
public void serialEvent(SerialPortEvent e) {
    try {
        String line = serialIn.readLine();
        String[] Values = line.split(",");
        power = Double.parseDouble(Values[1]);
        System.out.println(power / 5);
        }  //This works as expected and shows values on console
        fwdpower.setValue(power/5); //Shows NOTHING! UGHHHH!
    catch (IOException ex) {ex.printStackTrace();
    }
}

Now the HARD part: Has me completely frustrated!!

I am trying to now drive a gauge from the jfxtras gauges. I have all the proper libraries imported, and I create a very simple GUI in scenebuilder. Here is the XML file created:

<?xml version="1.0" encoding="UTF-8"?>

<?import eu.hansolo.enzo.gauge.RectangularGauge?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.Pane?>
<?import javafx.scene.layout.RowConstraints?>


<GridPane alignment="center" hgap="10" vgap="10"        xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8.0.65"            fx:controller="sample.Controller">
 <columnConstraints>
  <ColumnConstraints />
 </columnConstraints>
<rowConstraints>
<RowConstraints />
</rowConstraints>
<children>
  <Pane prefHeight="342.0" prefWidth="377.0">
     <children>
        <RectangularGauge fx:id="fwdpower" layoutX="25.0" layoutY="22.0"                         minValue="1.0" />    
     </children>
  </Pane>
  </children>
  </GridPane>

and this is the Controller: (nothing in it at the moment, since I do not want to have any buttons or anything like that...just display of data:

package sample;

import eu.hansolo.enzo.gauge.RectangularGauge;
import gnu.io.SerialPortEvent;
import javafx.fxml.FXML;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Controller {

 }

I have tried different combinations, but the guage refuses to show the data read from the serialPort. I think this might have to do with the GUI being on a different thread from main (have been searching and reading) but for the life of me I cant figure out how I might change my code to make this seemingly simple task work. All I want is for the gauge to display the data....I know I might be doing something completely stupid.....but cant figure this out.

Any ides as to how I might be able to achieve this?

PS: If I create an event handler in controller, with say a button, I am able to make the gauge move with an arbitrary value upon button press. Why cant I do the same when the serial event fires????

HELP PLEASE!!!!

The library you are using in not JFXtras but Enzo. Gerrit's old gauge library was part of JFXtras 2.x, but he decided to move the gauges to a library of his own; Enzo. That said, setting the value like you do should work. You can try to wrap it in Platform.runLater( () -> fwdpower.setValue(5) ); to make sure it runs on the graphical thread. Also try and divide by 5.0 instead of 5 (I'm always uncertain how doubles and int behavior when mixed). — tbeernot, Apr 09 '16 at 16:58
Thank you tbeernot...Yeah, thanks for pointing out the Library difference, however, the Gauges and library on Enzo's build seem to be working just fine. I have been trying combinations of Platform.runLater, after doing some digging, however when I add it to the serial event I get this: "Overrides method in java.lang.Runnable....and executing produces a java.lang.NullPointerException....any ideas? — CYBORGCNC, Apr 09 '16 at 17:17

score 0 · Accepted Answer · answered Apr 11 '16 at 23:44

@FXML-annotated fields are only initialized in the controller created by the FXMLLoader; you can't simply annotate a field in an arbitrary object and expect it to be initialized by the loader.

Create the annotated field in the controller and define a method to set it:

package sample;

import eu.hansolo.enzo.gauge.RectangularGauge;
import gnu.io.SerialPortEvent;
import javafx.fxml.FXML;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Controller {

    @FXML
    private RectangularGauge fwdpower ;

    public void setFwdPower(double power) {
        fwdpower.setValue(power);
    }
}

Then just get a reference to the controller and invoke the method on it. Note that since your serialEvent method is invoked from a background thread, you should wrap the call to the controller in Platform.runLater(...):

package sample;

import eu.hansolo.enzo.gauge.RectangularGauge;
import gnu.io.*;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.fxml.FXML;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;

import java.io.*;

public class Main extends Application implements SerialPortEventListener {

    SerialPort serialPort = null;
    private BufferedReader serialIn;
    private OutputStream serialOut;


    private Controller controller ;    

    @Override
    public void start(Stage primaryStage) throws Exception {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("sample.fxml"));
        Parent root = loader.load();

        controller = loader.getController();

        primaryStage.setTitle("Power Meter");
        primaryStage.setScene(new Scene(root, 380, 320));
        primaryStage.show();

        //
        CommPortIdentifier port = CommPortIdentifier.getPortIdentifier("COM60");
        CommPort commPort = port.open(this.getClass().getName(), 2000);
        serialPort = (SerialPort) commPort;
        serialPort.setSerialPortParams(115200, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
        serialIn = new BufferedReader(new InputStreamReader((serialPort.getInputStream())));
        serialPort.addEventListener(this);
        serialPort.notifyOnDataAvailable(true);
        //
    }


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

    @Override
    public void serialEvent(SerialPortEvent e) {
        try {
            String line = serialIn.readLine();
            String[] values = line.split(",");
            final double power = Double.parseDouble(values[1]);
            System.out.println(power / 5);
            Platform.runLater(() -> controller.setFwdpower(power/5));
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

}

JavaFX pass data to jfxtras gauge from Arduino

1 Answers1