First Java Program.md

First Java Program

Create Hello World Program

1. Create a new Java project in your IDE.
2. Create a new Java class in the project.
3. Write the following code in the class.

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

Output

Hello World

explain the code above

The first line

The first line of the code is the class declaration. The class name is HelloWorld.

• public is an access modifier. It means that the class is accessible from anywhere.
• class is a keyword in Java. It is used to declare a class.
• { and } are used to define the scope of the class.
• HelloWorld is the name of the class.

The second line

The second line is the main method declaration.

• public is an access modifier. It means that the method is accessible from anywhere.
• static is a keyword in Java. It means methods/attributes can be accessed without creating an object of a class.
• void is a keyword in Java. It means that the method does not return a value.
• main is the name of the method.
• () is used to define the parameters of the method.
• String[] args is the parameter of the method. It is an array of strings.
• { and } are used to define the scope of the method.
• System.out.println("Hello World"); is the body of the method. It prints the string "Hello World" to the console.
• ; is used to end a statement.

Don't Worry about the syntax for now. We will learn it in the next few weeks.

The third line

The third line is the closing bracket of the main method.

The fourth line

The fourth line is the closing bracket of the class.

Main Method

• The main method is the entry point of a Java program. It is the first method that is executed when the program is run.
• The main method must be declared in a public class.
• Each Java program must have only one main method.