Java Introduction - JAVA DEVELOPMENT Training By Om Sir

Let's create the hello java program:-

Save the above file as Simple.java.

To compile:	javac Simple.java
To execute:	java Simple

Output:

Hello Java

Compilation Flow:

When we compile Java program using javac tool, the Java compiler converts the source code into byte code.

Parameters used in First Java Program

Let's see what is the meaning of class, public, static, void, main, String[], System.out.println().

class keyword is used to declare a class in Java.
public keyword is an access modifier that 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 an object to invoke the static method. The main() method is executed by the JVM, so it doesn't require creating 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 the starting point of the program.
String[] args or String args[] is used for command line argument. We will discuss it in coming section.
System.out.println() is used to print statement. Here, System is a class, out is an object of the PrintStream class, println() is a method of the PrintStream class.