Java Programs Asked in Interview

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Java is a popular programming language, and questions related to Java are commonly encountered in technical interviews. Here's a compilation of Java programs that are frequently asked in interviews, ranging from basics to more challenging ones.

Well, this page includes the top 30+ frequently asked Java programs in interviews for beginners as well as experienced programmers.

30 Frequently Asked Java Programs in Interviews

All these Java programs have step-by-step explanations along with their output.

Java String Programs with Output

  1. Java Program to Find the First Non-repeated Character in a String
  2. Java Program to Check Palindrome String
  3. Java Program to Find Duplicate Characters in a String
  4. Java Program to Find Duplicate Words in a String
  5. Java Program to Find All the Permutations of a String
  6. Java Program to Count Occurrences of Words in a String
  7. Java Program to Count the Occurrences of Each Character
  8. Java Program to Count Vowels and Consonants in a String
  9. Java program to Count the Number of Duplicate Words in a String
  10. Java Program to Count Number of Words in Given String
  11. Java Program to Count the Number of Occurrences of Substring in a String
  12. Java Program to Count the Occurrences of Each Character in String
  13. Java Program to Merge Two String Arrays
  14. Java Program to Remove Duplicate Words from String
  15. Java Program to Reverse a String(5 ways)
  16. Java Program to Reverse Each Word of a String
  17. Java Program to Swap Two Strings
  18. How to Check if the String Contains Only Digits
  19. How to Check if the String Contains Only Letters
  20. How to Check If the String Contains Only Letters or Digits

Java Array Programs with Output

  1. Java Program to Reverse an Array Without Using Another Array
  2. Java Program to Find Duplicate Elements in an Array
  3. Java Program to Find Largest Number in an Array
  4. Java Program to Check the Equality of Two Arrays

Java Number Programs with Output

  1. Java Program to Find Sum of Natural Numbers
  2. Java Program to Reverse a Number
  3. Java Program to Find Prime Numbers
  4. Java Program to Check Armstrong Number
  5. Java Program to Count the Number of Digits in a Number
  6. Java Program for Prime Numbers Within a Range

Java Programs on OOP (Object-Oriented Programming) with Output

  1. Java Program to Calculate Salary of an Employee
  2. Java Program to Calculate Gross Salary of Employee

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Related Java Programs with Output and Explanations

Java Program to Find the First Non-repeated Character in a String Java Program to Check Palindrome String Java Program to Find Duplicate Characters in a String Java Program to Find Duplicate Words in a String Java Program to Find All the Permutations of a String Java Program to Count Occurrences of Words in a String Java Program to Count the Occurrences of Each Character Java Program to Count Vowels and Consonants in a String Java program to Count the Number of Duplicate Words in a String Java Program to Count Number of Words in Given String Java Program to Count the Number of Occurrences of Substring in a String Java Program to Count the Occurrences of Each Character in String Java Program to Merge Two String Arrays Java Program to Remove Duplicate Words from String Java Program to Reverse a String(5 ways) Java Program to Reverse Each Word of a String Java Program to Swap Two Strings How to Check if the String Contains Only Digits How to Check if the String Contains Only Letters How to Check If the String Contains Only Letters or Digits Java Program to Remove All Whitespaces from a StringJava Program to Check if a String is Empty or NullJava Program to Find Maximum Occurring Character in StringJava Program to Add Characters to a StringJava Program to Remove All Whitespaces from a StringJava Program to Check if a String is Empty or NullJava Program to Find Maximum Occurring Character in StringJava Program to Check if a Year is a Leap YearJava Program to Display Characters from A to Z using LoopJava Program To Count the Occurrences of Each Character Using HashMap Java Program to Reverse an Array Without Using Another Array Java Program to Find Duplicate Elements in an Array Java Program to Find Largest Number in an Array Java Program to Check the Equality of Two ArraysJava Program to Calculate Average Using ArraysJava Program to Sort the Array Elements in Descending Order Java Program to Find Factorial Using RecursionJava Program to Find Sum of Natural Numbers Java Program to Reverse a Number Java Program to Find Prime Numbers Java Program to Check Armstrong Number Java Program to Count the Number of Digits in a Number Java Program for Prime Numbers Within a RangeJava Program to Find the Largest of Three NumbersJava Program to Check if a Number is PrimeJava Program to Find the Fibonacci SeriesJava Program to Check if a Number is Positive or NegativeJava Program to Find GCD of Two NumbersJava Program to Find Strong NumberJava Program to Find LCM of Two NumbersJava Program to Check Palindrome NumberJava Program to Swap Two Numbers Without Using a Temp VariableJava Program to Find the Second Largest Number in an ArrayJava Program to Find GCD of Two NumbersJava Program to Find Strong NumberJava Program to Find LCM of Two NumbersJava Program to Check Palindrome NumberJava Program to Find the Largest of Three NumbersJava Program to Check if a Number is PrimeJava Program to Swap Two Numbers Without Using a Temp VariableJava Program to Find the Second Largest Number in an ArrayJava Program to Check if a Given Number is Perfect SquareJava Program to Find the Fibonacci SeriesJava Program to Check if a Number is Positive or Negative Java 8 Program to Find the Frequency of Each Character in a Given String Java 8 Program to Find the Maximum Number and Minimum Number in a List Java 8 Program to Find the Second Largest Number in the List of Integers Java 8 Program to Find the Age of a Person if the Birthday Date has Given Java 8 Program to Find the Sum of All Digits of a Number Java 8 Program to Print Even Numbers from a List Java 8 Program to Remove Duplicate Elements from a List Java 8 Program to Retrieve Last Element of a List of Strings Java 8 Program to Reverse Each Word of String Java 8 Program to Sort List of Strings Alphabetically Java Program for Diamond Shape Pattern Java Program to Print Character Pyramid Pattern Java Program to Print a Pyramid Java Program to Print an Inverted Pyramid Java Program to Print a Hollow Pyramid Java Program to Print a Diamond Pattern Java Program to Print a Right Triangle Star Pattern Java Program to Print an Inverted Right Triangle Star Pattern Java Program to Print a Left Triangle Star Pattern Java Program to Print a Pascal's Triangle Java Program to Print a Fibonacci Pyramid Java Program to Print a Number Pyramid Java Program to Print a Reverse Number Pyramid Java Program to Print a Hollow Square Pattern Java Program to Print a Cross (X) Pattern Java Program to Print a Plus (+) Pattern Java Program to Print a Butterfly Pattern Java Program to Print a Diamond Shape with Numbers Java Program to Print an Alphabet Pyramid Java Program to Print a Heart Shape Star Pattern Java Program to Calculate Salary of an Employee Java Program to Calculate Gross Salary of Employee Java Program to Reverse a Linked List Java Program to Reverse a Linked List Detecting a Cycle in a Linked List Using Java Finding the Middle Element of a Linked List using Java Merging Two Sorted Linked Lists using Java Queue Implementation in Java Using Array Queue Implementation in Java Using ArrayList Queue Implementation in Java Using LinkedList Queue Implementation in Java Using Two Stacks Priority Queue Implementation in Java Using Linked List Linked List Implementation in Java Using Arrays Doubly Linked List Implementation in Java Circular Linked List Implementation in Java Deque Implementation in Java Finding the Height of a Binary Tree in Java Determining if a Binary Tree is Balanced in Java Implementing Binary Search Tree (BST) Operations in Java Finding the Lowest Common Ancestor in a BST using Java Java Program to Perform Matrix Multiplication Java Program to Find Transpose of a Matrix Java Program to Add Two Matrices

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