JavaPrograms

A collection of small Java programs for practicing core programming concepts, data structures, algorithms, and common interview questions.

Topics

• Array: array splitting, merging, maximum pair sum, and finding largest values
• Concepts: type conversion, inheritance, method dispatch, super, and singleton patterns
• Interview questions: anagrams, duplicate values, vowels, missing numbers, reversing strings and arrays, and substring searches
• Numbers: Armstrong numbers, binary and decimal conversion, factorials, Fibonacci numbers, HCF, LCM, palindromes, primes, and swapping values
• Patterns: console output patterns using stars and numbers
• Search: linear search and binary search
• Sort: bubble sort and sorting with loops, collections, and built-in methods
• Strings: palindrome checks, removing unwanted characters, sorting characters, and swapping strings

Project structure

JavaPrograms/
├── src/       Java source files grouped by topic and package
├── bin/       Compiled `.class` files
└── JavaPrograms.iml

The package names match the folders under src, for example search, sort, Numbers, and Strings.

Requirements

• Java Development Kit (JDK) 8 or newer
• A command prompt, PowerShell, or an IDE such as IntelliJ IDEA or Visual Studio Code

Compile the project

From the project root, compile all source files into bin.

Windows PowerShell

New-Item -ItemType Directory -Force bin
javac -d bin (Get-ChildItem -Recurse -Filter *.java src | ForEach-Object { $_.FullName })

macOS/Linux

mkdir -p bin
javac -d bin $(find src -name "*.java")

Run a program

Most classes include a main method and can be run independently using their fully qualified class name:

java -cp bin search.BinarySearch
java -cp bin Numbers.FactorialLoop
java -cp bin Strings.PalindromeString

Replace the class name with another class from src to try a different example. Some programs use hard-coded sample values, so edit the corresponding source file when you want to experiment with different input.

Learning goals

This repository is intended for hands-on practice with:

• Java syntax and control flow
• Arrays and strings
• Recursion and iteration
• Searching and sorting algorithms
• Object-oriented programming fundamentals