This Java exercise collection is designed to deepen your understanding of Java and refine your coding skills. The programs provide hands-on experience in solving real-world problems, reinforce key concepts, and help you master Java fundamentals, including variables, control statements, arrays, strings, methods, and object-oriented programming.

• Covers Java practice problems from beginner to advanced levels.
• Helps strengthen Java programming and problem-solving skills.
• Includes programs based on numbers, patterns, arrays, and strings.

Java Beginner Exercises

These exercises focus on basic Java syntax, arithmetic operations, numbers, patterns, arrays, and simple string operations.

1. Write a Hello World Program in Java

Input: Hello World!
Output: Hello World!

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2. Write a Program in Java to Add two Numbers.

Input: 2 3
Output: 5

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3. Write a Program to Swap Two Numbers

Input: a=2 b=5
Output: a=5 b=2

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4. Write a Java Program to convert Integer numbers and Binary numbers.

Input: 9
Output: 1001

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5. Write a Program to Find Factorial of a Number in Java.

Input: 5
Output: 120

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6. Write a Java Program to Add two Complex Numbers.

Input: 1+2i
4+5i
Output: 5+7i

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7. Write a Program to Calculate Simple Interest in Java

Input : P = 10000 R = 5 T = 5
Output : 2500

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8. Write a Program to Find Sum of Fibonacci Series Number

Input: n = 4
Output: 33
Explaination: Sum of numbers at even indexes = 0 + 1 + 3 + 8 + 21 = 33.

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Java Exercise on Pattern

9. Write a Program to Print the Pascal's Triangle in Java

Input : N = 5

Output:

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10. Write a Program to Print Pyramid Number Pattern in Java.

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11. Write a Java Program to Print Pattern.

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12. Write a Java Program to Print Pattern.

Input : N = 5

Output:

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13. Java Program to Print Patterns.

Input: number = 7

Output:

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Java Intermediate Exercises

These exercises require more understanding of arrays, strings, searching techniques, and common algorithms.

14. Write a Java Program to Compute the Sum of Array Elements.

Input: [ 2, 4, 6, 7, 9]
Output: 28

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15. Write a Java Program to Find the Largest Element in Array

Input: [ 7, 2, 5, 1, 4]
Output: 7

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16. Write Java Program to Find the Tranpose of Matrix

Input:

[ [ 1, 2, 3 ]

[ 4, 5, 6 ]

[ 7, 8, 9 ] ]

Output:

[ [ 1, 4, 7]

[ 2, 5, 8]

[ 3, 6, 9] ]

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17. Java Array Program For Array Rotation

Input: arr[] = {1, 2, 3, 4, 5, 6, 7}, d = 2

Output:  3 4 5 6 7 1 2

Explaination: d=2 so 2 elements are rotated to the end of the array. So, 1 2 is rotated back

So, Final result: 3, 4, 5, 6, 7, 1, 2

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18. Java Array Program to Remove Duplicate Elements From an Array

Input: [ 1, 2, 2, 3, 3, 3, 4, 5 ]
Output: [ 1, 2, 3, 4, 5 ]

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19. Java Array Program to Remove All Occurrences of an Element in an Array

Input: array = [ 1, 2, 1, 3, 5, 1 ] , key = 1
Output: [2, 3, 5]

Explaination: all the occurrences of element 1 is removed from the array So, array becomes from

[ 1, 2, 1, 3, 5, 1 ] to
Final result: [2, 3, 5]

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String Exercises in Java

20. Java program to check whether a string is a Palindrome

Input: "racecar"
Output: Yes
Explaination: As racerar after reversing becomes racecar. As Reverse of String is same as String so it is Palindrome

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21. Java String Program to Check Anagram

Input: str1 = "Silent"
str2 ="Listen"
Output: Strings are Anagram
Explaination: As all the elements in str1 are exact same as to create str2 .
i.e., we can create str2 using elements of str1 without removing any element or removing any extra element.

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22. Java String Program to Reverse a String

Input: str= "Geeks"
Output: "skeeG"

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23. Java String Program to Remove leading zeros

Input : 00000123569
Output : 123569

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Java Advanced Searching and Sorting Exercises

These exercises involve fundamental searching and sorting algorithms and require a stronger understanding of algorithmic problem-solving.

24. Write a Java Program for Linear Search.

Time Complexity: O(N)
Space Complexity: O(N)

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25. Write a Binary Search Program in Java.

Time Complexity: O(logN)
Space Complexity: O(N)

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Practice Problems in Java Sorting Algorithms

26. Java Program for Bubble Sort.

Time Complexity: O(N ² )
Space Complexity: O(1)

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27. Write a Program for Insertion Sort in Java.

Time Complexity: O(N ² )
Space Complexity: O(1)

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28. Java Program for Selection Sort.

Time Complexity: O(N ² )
Space Complexity: O(1)

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29. Java Program for Merge Sort.

Time Complexity: O(N logN)
Space Complexity: O(N)

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30. Java Program for QuickSort.

Time Complexity: O(N logN)
Space Complexity: O(1)

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