Reverse number in Java using function

Reverse number in Java using function

In this blog, we delve into the essential task of reversing numbers in Java programming, with a specific focus on utilizing functions. Reverse number in Java using Function is a fundamental operation with numerous applications in Java programming, ranging from cryptography to mathematical calculations. By harnessing the power of functions, we aim to provide a comprehensive understanding of how to efficiently reverse a number in Java.


To reverse number in Java using function, follow these steps:

1. Define a function to reverse the digits of a given number.

2. Inside the function, extract the digits of the number and append them in reverse order.

3. Return the reversed number to the calling function for further processing.

Code- Reverse number in Java using function

public class ReverseNumber {
// Function to reverse the digits of a given number
public static int reverse(int num) {
int reversedNum = 0;
while (num != 0) {
int digit = num % 10;
reversedNum = reversedNum * 10 + digit;
num /= 10;
return reversedNum;
public static void main(String[] args) {
int num = 1234; // Input number
int reversedNum = reverse(num); // Call the reverse function
System.out.println("Reversed Number: " + reversedNum);

Explanation of the code:

The Java code defines a class called ReverseNumber, which has a static method called reverse that returns the reversed integer from an integer input.

– The reverse method initializes a variable reversedNum to store the reversed number.

– Inside a while loop, the last digit of the input number num is extracted using the modulus operator % and stored in the variable digit.

– The extracted digit is appended to the reversedNum variable by multiplying it by 10 and adding the digit.

– The last digit is then removed from the input number num by integer division /.

– This process continues until num becomes zero.

– Finally, the reversed number stored in the reversedNum variable is returned.

The main method defines an input number (1234) and calls the reverse method, returning the reversed number and printing it to the console.


Reversed Number: 4321

Dive into the world of Java programming and master the reverse number in java using for loop in a snap!

Performance Analysis & Optimization Techniques for Reverse number in Java using function:

1. Time Complexity Analysis: 

The function’s time complexity is O(log N), where N represents the input number’s digits, and it’s crucial to comprehend how this complexity increases with input size.

2. Space Complexity Analysis:

The function’s space complexity is O(1), as it uses a constant extra space regardless of the input size. 

3. Benchmarking and Profiling:

Use benchmark tests to measure function execution time for different input sizes and profiling tools like JVisualVM or YourKit to identify performance bottlenecks.

4. Input Validation Optimization:

Efficient input validation techniques can prevent unnecessary computation and enhance overall performance by handling invalid inputs at the beginning of a function.

5. Avoiding Redundant Computations:

The algorithm should be thoroughly analyzed to identify and eliminate redundant computations, such as caching results for previously processed inputs to prevent recomputation.

6. Bit Manipulation Techniques:

Explore bitwise operations for reversing numbers, as bit manipulation techniques can sometimes provide more efficient solutions than arithmetic operations.

7. Optimizing Loops:

The loop structure and conditions should be optimized for performance by reducing iterations and avoiding unnecessary comparisons or operations within the loop.

8. Inlining and Loop Unrolling:

Inlining small functions and loop unrolling can reduce function call overhead and improve loop performance, thereby enhancing the efficiency of the reverse number function.

9. Using Primitives Instead of Objects:

Use primitive data types like int for numeric variables instead of Integer to reduce memory overhead and improve performance.

10. Compiler Optimization Flags:

Compiler optimization flags (-O2, -O3) are used to instruct the compiler to apply optimizations during compilation, resulting in faster executable code.

Understand the Concept of Reverse number in Java using while loop, Here!

11. Parallelization:

Utilize parallelization techniques to distribute computation across multiple threads or cores, potentially improving performance in batch processing of multiple numbers, despite not benefiting reversing a single number.

12. Profiling and Iterative Refinement:

The function’s performance is continuously evaluated and refined iteratively, identifying hotspots for optimization and directing efforts towards critical areas.

In conclusion, this blog ’Reverse number in Java using function’ provided a comprehensive overview of reversing numbers in Java using functions, emphasizing its educational and practical significance. Readers are encouraged to explore further programming activities and continue their learning journey with Newtum’s user-friendly tutorials and courses across various programming languages. Happy coding!

Reverse number in Java using function- FAQ

1. How can I reverse number in Java using function?

Answer: Utilize the provided function reverse() in the ReverseNumber class to reverse any integer input.

2. What is the importance of reverse number in Java using function?

Answer: Reversing numbers is crucial for tasks like cryptography, mathematical operations, and data manipulation.

3. Is reversing a number in Java using a function efficient?

Answer: Yes, using a function improves code organization and reusability, enhancing overall program efficiency.

4. Can I reverse negative numbers in Java using a function?

Answer: Absolutely, the function handles negative numbers seamlessly using arithmetic operations.

5. Are there any performance considerations when reversing numbers using a function?

Answer: Yes, optimizing the function can improve performance, especially for large numbers and frequent invocations.

6. Can reversing numbers using functions be parallelized?

Answer: While reversing a single number may not benefit from parallelization, batch processing of multiple numbers can leverage parallelization techniques for improved performance.

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