📘 Java Programs
Practice core Java programming with small, focused problems. These programs cover numbers, strings, arrays, and pattern printing — perfect for interviews, coding rounds, and strengthening logic building.
🔢 Number Programs
📅 Check Leap Year
Determine whether a year is a leap year in Java using simple conditional logic and modular arithmetic.
🔁 Palindrome Number
Reverse the digits of a number and compare with the original to check if it is a numeric palindrome.
🔢 Prime Number
Check whether a number is prime using loops, divisibility checks, and optimized boundaries in Java.
💪 Armstrong Number
Detect Armstrong numbers by summing powered digits and comparing with the original value.
📈 Fibonacci Series
Generate Fibonacci series in Java using loops and recursion with clear step-by-step examples.
✖️ Factorial in Java
Calculate factorial of a number using iterative and recursive approaches with edge case handling.
🔤 String Programs
🔄 Palindrome String
Check if a string is a palindrome by reversing characters or using two-pointer comparison logic.
🔁 Reverse a String
Reverse strings using loops, StringBuilder, and recursion with time-complexity discussion.
🔢 String Contains Only Digits
Validate if a string has only numeric characters using regex, iteration, and built-in methods.
🔍 First Non-Repeated Character
Find the first non-repeating character in a string using maps and frequency counting.
🧮 Check Anagram Strings
Verify whether two strings are anagrams using sorting or frequency arrays/HashMap.
🔄 Longest Palindromic Substring
Find the longest palindrome substring using expand-around-center and other approaches.
📈 Character Occurrence Count
Count frequency of characters in a string using HashMap and clean output formatting.
📚 Array Programs
✅ Check if Array is Sorted
Check whether an array is sorted in ascending or descending order using simple loops.
🔍 Find Duplicates in Array
Detect duplicate elements in an array using nested loops, HashSet, and frequency maps.
🔄 Reverse Array
Reverse array elements in-place using two-pointer technique or Collections utilities.
🥈 Second Largest in Array
Find the second largest element with and without sorting, including edge case handling.
📊 Sort Array Without Built-ins
Sort arrays manually using bubble sort, selection sort, and insertion sort logic in Java.
🚫 Remove Duplicates from Array
Remove duplicate elements using Set and in-place two-pointer style techniques.
✨ Pattern Printing Programs
🔺 Pascal’s Triangle
Print Pascal’s triangle using nested loops and understand binomial coefficient logic.
🔷 Diamond Star Pattern
Display a symmetric diamond-shaped star pattern using spaces and nested loops.
🔺 Pyramid Star Pattern
Print pyramid-shaped star patterns with centered alignment and increasing rows.
📐 Right-Angled Triangle Pattern
Generate right-angled triangle star patterns using nested loops and row/column logic.
📺 Practice Java with Video Walkthroughs
Watch step-by-step explanations of Java programs, patterns, and interview-style problems.
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