Java NetBeans sending value and receiving value from Arduino

Question

This is my Java code to send a value to Arduino and a receiving value from Arduino. Can anyone tell where I made a mistake? I am able to send the value but can't receive a value from Arduino.

package hell;

import com.panamahitek.ArduinoException;
import com.panamahitek.PanamaHitek_Arduino;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

public class led extends javax.swing.JFrame 
{
    PanamaHitek_Arduino Arduino  = new PanamaHitek_Arduino();
    private BufferedReader input;
    SerialPort serialPort;

    public led(){
        initComponents();
        try {
            Arduino.arduinoTX("com3", 115200);
        } 
        catch (ArduinoException ex) {
            Logger.getLogger(led.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public synchronized void close() {
        if (serialPort != null) {
            serialPort.removeEventListener();
            serialPort.close();
        }
    }

    public synchronized void serialEvent(SerialPortEvent oEvent) 
    {
        System.out.println("lol 31");
        if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
            try {
                System.out.println("lol 1.1");
                Scanner s = new Scanner(serialPort.getInputStream());
                int mes =Integer.parseInt( s.nextLine());
                System.out.println(mes);
                System.out.println("lol 1");
            } catch (Exception e) {
                System.err.println(e.toString());
                System.out.println("Syncronice ");
            }
        }
        // Ignore all the other eventTypes, but you should consider the other ones.
    }

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try{
            Arduino.sendByte(0);
        }
        catch(Exception ex){
            Logger.getLogger(led.class.getName()).log(Level.SEVERE,null, ex);
        }
        System.out.println("led is off");
    }                                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try{
            Arduino.sendByte(1);
        }
        catch(Exception ex){
            Logger.getLogger(led.class.getName()).log(Level.SEVERE,null, ex);
        }
        System.out.println("led is on");
    }          

    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new led().setVisible(true);
            }
        });
    }

    private javax.swing.JButton jButton1;

    try{
        Arduino.sendByte(1);
    }
    catch(Exception ex){
        Logger.getLogger(led.class.getName()).log(Level.SEVERE,null, ex);
    }

    System.out.println("led is on");

    private javax.swing.JButton jButton2;
}

Here is my Arduino code, which receives a value from Java and prints it accordingly:

int val = 0;
int led = 8;

void setup() {
  Serial.begin(112500);
  pinMode(led, OUTPUT);
}

void loop() {
  if (Serial.available()>0) {
    val = Serial.parseInt();
    if(val == 1) {
      //Switch on the LED, if the received value is 1.
      digitalWrite(led, HIGH);
      Serial.println("Succesfully received.");
    } else if(val == 0) {
      //Switch off the LED, if the received value is 1.
      digitalWrite(led, LOW);
    }
  }
}

EDIT: There is no problem to controlling arduino via Java code, the problem is that I can't received message from Arduino to display in a Java.

Answer 1

You are writing a number as a single byte and expect it as a string on the other end.

Replace

val = Serial.parseInt();

with

val = Serial.read();