Run Java Program in Ubuntu 18.04

Run Java Program in Ubuntu 18.04. The program will be run using Oracle's OpenJDK JDK 8.

• Check if Java Runtime Environment(JRE) is installed in machine:

  java -version
  

  If JRE is installed it will show the version information similar to following:

  openjdk 11.0.5 2019-10-15
  OpenJDK Runtime Environment (build 11.0.5+10-post-Ubuntu-0ubuntu1.118.04)
  OpenJDK 64-Bit Server VM (build 11.0.5+10-post-Ubuntu-0ubuntu1.118.04, mixed mode)
  

  If you do not have installed JRE, install JRE using:

  sudo apt-get install openjdk-8-jre
  

• Check if Java compiler is installed in machine:

  javac -version
  

  If Java compiler is installed it will show the version information similar to following:

  javac 1.8.0_232
  

  If you do not have installed Java compiler, install it using:

  sudo apt-get install openjdk-8-jdk
  

• Go to any directory and create a demo Java program. For example, we are going to create Student.java as following:

  class Student{
  	public static void main(String[] args){
  		System.out.println("Hello from Student class");
  	}
  }
  

• Compile the Java class using:

  javac Student.java
  

• Run the compiled program using:

  java Student
  

  You will see the output like below:

  Hello from Student class
  

Reference:

• OpenJDK documentation for Installing OpenJDK