Java Day 1: Introduction to Java & Setup

Goal of this Day

Today you will learn:

• What Java is and why it is used
• How to install the Java Development Kit (JDK)
• How to set up an IDE
• The basic structure of a Java program

By the end, you will be able to run your first Java program.

Step 1: What is Java?

Java is a popular programming language used for many types of applications.

Examples:

• Web applications
• Mobile apps (Android)
• Desktop software
• Game development

Why use Java?

• Platform independent ("Write once, run anywhere")
• Object-oriented
• Widely used in industry

Step 2: Installing Java (JDK)

To write and run Java programs, you need the Java Development Kit (JDK).

Steps:

• Download the JDK from the official Java website
• Install it on your computer
• Set up environment variables (optional but recommended)

Step 3: Setting up an IDE

An IDE (Integrated Development Environment) helps you write code more easily.

Popular IDEs:

• IntelliJ IDEA
• Eclipse
• Visual Studio Code

Choose one and install it.

Step 4: Structure of a Java Program

Every Java program follows a specific structure.

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

Explanation:

• public class HelloWorld → Defines the class
• main → Entry point of the program
• System.out.println() → Prints text to the console

Practice

Write your first Java program:

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

Exercise

Modify the program so that it prints:

• Your name
• Your age
• Your favorite hobby

Example:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("My name is Alex");
        System.out.println("I am 16 years old");
        System.out.println("My hobby is programming");
    }
}