Learn Java

A structured collection of Java programs covering fundamental programming concepts. Each example is designed to demonstrate core Java features through practical, runnable code.

Topics Covered

Introduction

• HelloWorld - Basic output and program structure
• Variables - Variable declaration and data types
• UserInput - Reading input with Scanner
• Math - Mathematical operations and calculations
• Casting - Type conversion and casting
• FormattedOutput - String formatting and output

Conditionals

• Conditionals - If-else statements and decision making

Loops

• Loops - For, while, and do-while loops
• Nested - Nested loop patterns

Methods

• Methods - Function definition and calling

Arrays

• Arrays - Array creation, manipulation, and iteration
• Dimensions - Multi-dimensional arrays
• Grid - Working with 2D arrays and grids

Problems

• Nums - Practice problems and exercises

Projects

• Workouts - Workout tracking application

Quick Start

Prerequisites

• Java Development Kit (JDK) 8 or higher
• Make (for using the Makefile)

Running Examples

Each example can be run using the provided Makefile commands:

# Introduction examples
make hello          # Hello World program
make variables      # Variable examples
make input          # User input example
make calc           # Math operations
make cast           # Type casting
make format         # Formatted output

# Conditionals
make condition      # If-else statements

# Loops
make loops          # Loop examples
make nested         # Nested loops

# Methods
make methods        # Method examples

# Arrays
make arrays         # Array examples
make ds             # Multi-dimensional arrays
make grid           # 2D array grids

# Problems
make nums           # Practice problems

# Projects
make project        # Workout tracking app

Cleaning Up

Remove all compiled .class files:

make clean

Learning Path

Recommended order for beginners:

1. Start with introduction/ - Learn the basics
2. Move to conditionals/ - Understand decision making
3. Practice loops/ - Master iteration
4. Explore methods/ - Write reusable code
5. Work with arrays/ - Handle collections of data
6. Try problems/ - Apply what you've learned
7. Build projects/ - Create complete applications

Development

Adding New Examples

1. Create a new .java file in the appropriate directory
2. Add a corresponding Makefile target
3. Follow the package naming convention (package name = directory name)

Code Style

• Each file is self-contained with a main method
• Packages match directory names
• Clear, educational code with minimal complexity
• Interactive examples use Scanner for input