Unit 5: Understanding the first Java Programming

Understanding the first Java Programming

Prerequisite – JDK – java Development Kit

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

save this file as Simple.java
To compile: javac Simple.java
To execute: java Simple

- class keyword is used to declare a class in java.
- public keyword is an access modifier which represents visibility, it means it is visible to all.
- static is a keyword if we declare any method as static, it is known as the static method. The core advantage of the static method is that there is no need to create the object to invoke the static method. The main method is executed by the JVM, so it doesn't require to create an object to invoke the main method. So it saves memory.
- void is the return type of the method, it means it doesn't return any value.
- main represents startup of the program.
- String[] args is used for command line argument. We will learn it later.
- System.out.println() is used print statement. We will learn about the internal working off  System.out.println statement later.