Java Exercises - Basic to Advanced Java Practice Programs with Solutions
Last Updated :
09 Oct, 2025
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.
1. Write a Hello World Program in Java
Input: Hello World!
Output: Hello World!
2. Write a Program in Java to Add two Numbers.
Input: 2 3
Output: 5
3. Write a Program to Swap Two Numbers
Input: a=2 b=5
Output: a=5 b=2
4. Write a Java Program to convert Integer numbers and Binary numbers.
Input: 9
Output: 1001
5. Write a Program to Find Factorial of a Number in Java.
Input: 5
Output: 120
6. Write a Java Program to Add two Complex Numbers.
Input: 1+2i
4+5i
Output: 5+7i
7. Write a Program to Calculate Simple Interest in Java
Input : P = 10000 R = 5 T = 5
Output : 2500
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.
Java Exercise on Pattern
9. Write a Program to Print the Pascal's Triangle in Java
Input : N = 5
Output:
10. Write a Program to Print Pyramid Number Pattern in Java.
pattern-211. Write a Java Program to Print Pattern.
Pattern-312. Write a Java Program to Print Pattern.
Input : N = 5
Output:
pattern-413. Java Program to Print Patterns.
Input: number = 7
Output:
Pattern-5Array Exercises in Java
14. Write a Java Program to Compute the Sum of Array Elements.
Input: [ 2, 4, 6, 7, 9]
Output: 28
15. Write a Java Program to Find the Largest Element in Array
Input: [ 7, 2, 5, 1, 4]
Output: 7
Click Here for the Solution
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] ]
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
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 ]
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]
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
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.
22. Java String Program to Reverse a String
Input: str= "Geeks"
Output: "skeeG"
23. Java String Program to Remove leading zeros
Input : 00000123569
Output : 123569
Java Practice Problems for Searching Algorithms
24. Write a Java Program for Linear Search.
Time Complexity: O(N)
Space Complexity: O(N)
25. Write a Binary Search Program in Java.
Time Complexity: O(logN)
Space Complexity: O(N)
Practice Problems in Java Sorting Algorithms
26. Java Program for Bubble Sort.
Time Complexity: O(N 2 )
Space Complexity: O(1)
27. Write a Program for Insertion Sort in Java.
Time Complexity: O(N 2 )
Space Complexity: O(1)
28. Java Program for Selection Sort.
Time Complexity: O(N 2 )
Space Complexity: O(1)
29. Java Program for Merge Sort.
Time Complexity: O(N logN)
Space Complexity: O(N)
30. Java Program for QuickSort.
Time Complexity: O(N logN)
Space Complexity: O(1)
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