Serial Monitor Arduino Not Working In Arch Linux

I had difficulty when I first used Arduino IDE on Arch Linux, before I used Arduino IDE on Ubuntu and everything went smoothly.

I feel confused by this situation, Serial Monitor Arduino Not Working. Data from the microcontroller does not appear in the Serial Monitor.

Serial Monitor Testing Program Code

I tried with the Arduino blink example program that I modified as follows:

/*
  Blink

  Turns an LED on for one second, then off for one second, repeatedly.

  Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO
  it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN is set to
  the correct LED pin independent of which board is used.
  If you want to know what pin the on-board LED is connected to on your Arduino
  model, check the Technical Specs of your board at:
  https://www.arduino.cc/en/Main/Products

  modified 8 May 2014
  by Scott Fitzgerald
  modified 2 Sep 2016
  by Arturo Guadalupi
  modified 8 Sep 2016
  by Colby Newman

  This example code is in the public domain.

  http://www.arduino.cc/en/Tutorial/Blink
*/

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(9600);
}

// the loop function runs over and over again forever
void loop() {
  Serial.println("ON");
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  Serial.println("OFF");
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

I opened the serial monitor and did not get Serial data as shown in the following image:

Why Serial Monitor Arduino Not Working In Linux?

I find out in forums of why this is not working. And I found the problem in Arch Linux is in the java version.

Here is the version that I am using:

I am using Arduino Version 1.8.12 and using Java version JDK 8. Then I double-check whether in my Arch Linux there is another java version. I checked using the terminal:

How to Fix Serial Monitor Arduino Not Working?

It turned out that on my computer there are two versions of java, Java 8 and Java 13. By default Java is Java 8. Then I set Java to Java 13, with the command:

After that, check again whether the java used has become Java 13? Use the following command:

Restart your Arduino IDE. Then I reopened Serial Monitor and Success. But for the Serial Monitor display is not as beautiful as in Java 8. But thankful this has been successful.

Now I have fixed the Arduino Serial Monitor Not Working. Hopefully this article is useful. That's all.