Chapter 1: Programming Fundamentals & Java Basics

Introduction

Before building enterprise applications, it is important to understand the fundamentals of programming and the Java language.

Every software application, regardless of its size, is built using the same core programming concepts:

Variables
Data Types
Operators
Control Statements
Loops
Functions
Input and Output

These concepts form the foundation upon which modern software systems are built.

In this chapter, we will learn the fundamental building blocks of programming and understand how Java programs are written, compiled, and executed.

Throughout this tutorial, we will gradually build components of the Institute Placement Management System (IPMS) while learning Java concepts.

What You Will Learn

By the end of this chapter, you will:

Understand what programming is
Understand how software applications work
Learn programming language categories
Understand Java fundamentals
Install and verify Java Development Kit (JDK)
Write your first Java program
Understand Java program structure
Learn variables and data types
Use operators
Perform input and output operations
Understand type conversion
Build simple Java applications

What is Programming?

Programming is the process of writing instructions that tell a computer how to perform a task.

These instructions are called:

Programs

A program consists of a sequence of instructions executed by a computer.

Examples:

ATM Software
Banking Systems
Placement Portals
E-Commerce Applications
Mobile Apps

All of these applications are created using programming languages.

Why Do We Need Programming?

Programming helps us:

Automate repetitive tasks
Process large amounts of data
Solve business problems
Build software applications
Integrate systems
Improve efficiency

Without programming, modern software systems would not exist.

Evolution of Programming Languages

Programming languages have evolved significantly over the years.

Programming Language Evolution

First Generation Languages (1GL)

Machine Language

Characteristics:

Binary instructions
Difficult to understand
Hardware dependent

Example:

10101010
11110000

Second Generation Languages (2GL)

Assembly Language

Characteristics:

Uses mnemonics
Easier than machine language
Hardware dependent

Example:

MOV A, B
ADD A, C

Third Generation Languages (3GL)

Examples:

C
C++
Java
Python
C#

Characteristics:

Human readable
Portable
Easy to maintain

Why Java Became Popular

Java introduced a revolutionary concept:

Write Once, Run Anywhere

This means Java programs can run on different operating systems without modification.

Supported platforms include:

Windows
Linux
macOS

Understanding Java

Java is an object-oriented programming language developed by Sun Microsystems.

Today Java is maintained by Oracle.

Java is widely used for:

Enterprise Applications
Banking Systems
Insurance Platforms
E-Commerce Solutions
Cloud Applications
Android Applications
Microservices

Features of Java

Java provides several advantages:

Platform Independent
Object-Oriented
Secure
Robust
Multithreaded
Distributed
Portable
High Performance

Java Editions

Java is available in multiple editions.

Edition	Purpose
Java SE	Standard Applications
Jakarta EE	Enterprise Applications
Java ME	Embedded Devices

For this tutorial we will use:

Java SE

Understanding JDK, JRE and JVM

Many beginners confuse these three terms.

JVM

JVM stands for:

Java Virtual Machine

Responsible for executing Java bytecode.

JRE

JRE stands for:

Java Runtime Environment

Provides libraries and runtime environment.

JDK

JDK stands for:

Java Development Kit

Contains:

Compiler
Debugger
JVM
JRE
Development Tools

Relationship Between JDK, JRE and JVM

JDK
 │
 └── JRE
       │
       └── JVM

Installing Java

Download latest JDK:

https://jdk.java.net

https://www.oracle.com/java

Install the latest LTS version.

Recommended:

JDK 21

Verify Installation

Open Terminal:

java -version

Expected Output:

java version "21"

First Java Program

Create:

HelloWorld.java

public class HelloWorld {

    public static void main(String[] args) {

        System.out.println("Hello Java");
    }
}

Understanding the Program

Statement	Purpose
class	Defines class
main()	Entry point
System.out.println()	Prints output

Java Program Execution Flow

Step 1

Write Source Code

HelloWorld.java

Step 2

Compile

javac HelloWorld.java

Produces:

HelloWorld.class

Step 3

Execute

java HelloWorld

Step 4

JVM Executes Bytecode

Output:

Hello Java

Variables

Variables store data.

Example:

int age = 21;

Variable Naming Rules

Valid:

studentName
totalMarks
salary

Invalid:

1student
class
total marks

Data Types

Java supports two categories.

Primitive Data Types

Type	Size
byte	1 Byte
short	2 Bytes
int	4 Bytes
long	8 Bytes
float	4 Bytes
double	8 Bytes
char	2 Bytes
boolean	True/False

Examples

int age = 21;

double percentage = 82.50;

char grade = 'A';

boolean placed = true;

Reference Data Types

Examples:

String
Arrays
Objects

String studentName = "John Doe";

Operators

Operators perform operations on data.

Arithmetic Operators

+
-
*
/
%

Example:

int total = 10 + 20;

Relational Operators

==
!=
>
<
>=
<=

Example:

marks >= 60

Logical Operators

&&
||
!

User Input

Java provides Scanner class.

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        System.out.println("Enter Name:");

        String name = scanner.nextLine();

        System.out.println(name);
    }
}

Type Conversion

Implicit Conversion

int value = 10;

double result = value;

Explicit Conversion

double value = 100.50;

int result = (int)value;

IPMS Example

Let us create our first Placement Student record.

public class Student {

    public static void main(String[] args) {

        String name = "John Doe";

        int age = 21;

        double cgpa = 8.5;

        boolean eligible = true;

        System.out.println("Name: " + name);

        System.out.println("Age: " + age);

        System.out.println("CGPA: " + cgpa);

        System.out.println("Eligible: " + eligible);
    }
}

Best Practices

Use meaningful variable names
Follow Java naming conventions
Keep methods small
Write readable code
Use proper indentation

Common Beginner Mistakes

Mistake	Correct Approach
Missing semicolon	Add ;
Wrong class name	Match filename
Incorrect data type	Use proper type
Forgetting main()	Define entry point
Using reserved keywords	Use valid identifiers

Practice Exercises

Create a program to display student information.
Calculate total marks and percentage.
Accept user input for student details.
Convert temperature from Celsius to Fahrenheit.
Calculate placement eligibility based on CGPA.

Mini Assignment

Build a simple Student Registration Console Program.

Capture:

Student Name
Age
CGPA
Branch

Display all details on screen.

Chapter Summary

In this chapter, you:

Learned programming fundamentals
Understood Java basics
Installed Java
Created your first Java program
Learned variables and data types
Used operators
Accepted user input
Performed type conversion
Built a simple IPMS student program

In the next chapter, we will learn Object-Oriented Programming concepts including:

Classes
Objects
Constructors
Encapsulation