# Simplest Java communication

**URL:** <https://forum.arduino.cc/t/simplest-java-communication/439185>\
**Category:** Programming\
**Created:** [February 19, 2017, 8:44pm UTC](https://forum.arduino.cc/t/simplest-java-communication/439185 "2017-02-19T20:44:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![ludkokanta](https://avatars.discourse-cdn.com/v4/letter/l/e480ec/32.png) [@ludkokanta](https://forum.arduino.cc/u/ludkokanta)\
**Post date:** [February 19, 2017, 8:44pm UTC](https://forum.arduino.cc/t/simplest-java-communication/439185/1 "2017-02-19T20:44:51Z")

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I'd like to use the JSerialComm library to communicate between Java and an Arduino UNO. What is the simplest way?

It's just for simple automation so I need to send just a char or an int to serial port and pick it up in the Arduino to tell it which relays to turn on.

I looked at finished online projects and came up with this. Port is COM5

chosenPort = SerialPort.getCommPort("COM5");  
[//chosenPort.setComPortTimeouts](https://chosenPort.setComPortTimeouts)(SerialPort.TIMEOUT\_SCANNER, 0, 0); //dunno  
chosenPort.setBaudRate(9600);  
System.out.println(chosenPort.getBaudRate());  
chosenPort.openPort();  
System.out.println("TEST1");  
try {Thread.sleep(5000); } catch(Exception e) {}  
System.out.println(chosenPort.isOpen());  
if(chosenPort.openPort()) {

PrintWriter output = new PrintWriter(serialPort.getOutputStream()); ETC

Sometimes the port opens, mostly it doesn't. And when it did I didn't pick up anything on Arduino serial monitor... On the sketch I made a method with

if (Serial.available() == 1) {  
int serialData = Serial.read();  
Serial.println(serialData);

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**Author:** ![Robin2](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/robin2/32/216045_2.png) [@Robin2](https://forum.arduino.cc/u/Robin2)\
**Post date:** [February 19, 2017, 9:26pm UTC](https://forum.arduino.cc/t/simplest-java-communication/439185/2 "2017-02-19T21:26:12Z")

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I know very little Java.

The examples in [Serial Input Basics](http://forum.arduino.cc/index.php?topic=396450.0) are simple reliable ways to receive data into the Arduino. The technique in the 3rd example will be most reliable. I recommend that you get your Java program to output data in that style.

...R

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**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\
**Post date:** [May 5, 2021, 10:21pm UTC](https://forum.arduino.cc/t/simplest-java-communication/439185/3 "2021-05-05T22:21:14Z")

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