Basic Structure of a Java Program:

Tutorial 2 --- Understanding our First Java Hello World Program

In our previous tutorial we made our first JAVA program, but we didn’t understand anything, so this tutorial is the anatomy of our previous tutorial’s program’

 

Here’s the CODE:

 

package com.company;

public class Main {

    public static void main(String[] args) {
   // write your code here
        System.out.println("Hello World");
    }
}

 

ANATOMY:

package com.company;

A package in Java is used to group related classes. Think of it is as a folder in a file directory.

The company is function, all functions have their classes; Here the company function’s class is main

What is a Function?

A method is a block of code which only runs when it is called. You can pass data, known as parameters, into a method. Methods are used to perform certain actions, and they are also known as functions.

public class Main {

What is a Class?

 A class--the basic building block of an object-oriented language such as Java--is a template that describes the data and behavior associated with instances of that class. When you instantiate a class you create an object that looks and feels like other instances of the same class.

public static void main(String[] args) {

Here the main() method is the entry into the application.

We didn’t use any functions in here, instead we used the keyword static. Static means we don’t have to make class/object to run this program.

In void main(), void is to tell us that it’ll not return any value from the program, void means the value is empty.

public here is a access modifier, that means can use this program from anywhere, we will discuss more of this in our next tutorials.  

// write your code here
        System.out.println("Hello World");

In this section our code will execute. We write in this area for code execution.

// write your code here

This line is called a comment, a comment is a line in a code which ignored by the interpreter/compiler. This a single line comment. We will know more about comments in our next tutorials.

        System.out.println("Hello World");

This the print function.

You can see that we used class Main’s M in upper case and in below function’s m as lower case; here we’ve used “Naming conventions”.

For classes we use PascalConvention.

Example – AddTwoNumbers

For functions we use camelCaseConvention

          Eaxmple - addTwoNumbers