Java Exercises - Basic to Advanced Java Practice Programs with Solutions
Last Updated :
08 Sep, 2025
This Java exercise is designed to deepen your understanding and refine your Java coding skills, these programs offer hands-on experience in solving real-world problems, reinforcing key concepts, and mastering Java programming fundamentals.
Java enthusiasts can also benefit from practicing various java exercises on the GeeksforGeeks Online Practice Platform, where challenges cater to both beginners and advanced programmers.
1. Write Hello World Program in Java
The solution to the Problem is mentioned below:
Java
// Java Program to Print
// Hello World
import java.io.*;
// Driver Class
class GFG {
// main function
public static void main(String[] args)
{
// Printing Hello World
System.out.println("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 Print the Pascal's Triangle in Java
Input : N = 5
Output:
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
Click Here for the Solution
9. 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.
Click Here for the Solution
Java Exercise on Pattern
10. Write a Program to Print Pyramid Number Pattern in Java.
*
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*****
*******
Click Here for the Solution
11. Write a Java Program to Print Pattern.
* * * * * *
* *
* *
* *
* *
* * * * * *
12. Write a Java Program to Print Pattern.
1
2 1 2
3 2 1 2 3
4 3 2 1 2 3 4
5 4 3 2 1 2 3 4 5
6 5 4 3 2 1 2 3 4 5 6
13. Java Program to Print Patterns.
*
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*****
*******
*********
***********
*********
*******
*****
***
*
Array 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 Click Here for the Solution
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
Click Here for the Solution
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.
Click Here for the Solution
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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