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
```