Program to reverse a String without using StringBuilder

🔁 Reverse a String in Java (Without Using StringBuilder.reverse())

🧩 What problem are we solving?

The goal is to reverse the characters of a given string manually — without using built-in helper methods like StringBuilder.reverse().

This exercise helps understand string manipulation, loops, and index-based access in Java.

For example:
If the input is

"My Name is Vinod"

Then the output will be

"doniV si emaN yM"

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⚙️ How it works (step by step)

1. Start with an input string, e.g. "My Name is Vinod".

2. Initialize an empty string reverse = "".

3. Loop backward from the end of the string (str.length() - 1) to the beginning (0).

4. For each character:

   • Append it to reverse.

5. Once the loop completes, reverse will contain the reversed text.

6. Print the reversed string.

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🧠 Example Walkthrough

Step	Current Index	Character	Reverse String
1	15	d	d
2	14	o	do
3	13	n	don
4	12	i	doni
5	11	V	doniV
6	10	(space)	doniV
…	…	…	…
Final	0	M	doniV si emaN yM

✅ Final Output:
doniV si emaN yM

package com.vinod.test;


/**
 * Example to reverse a String without using StringBuilder reverse method.
 *@authorvinodkariyathungalkumaran
 *
 */
public class ReverseStringExample {

    public static void main(String[] args) {
        String str = "My Name is Vinod";
        System.out.println("Input=" + str);
        String reverse = "";
        for (int i = str.length() - 1; i >= 0; i--) {
            reverse = reverse + str.charAt(i);
        }
        System.out.println("Output=" + reverse);
    }

}

Ouput

Input=My Name is Vinod
Output=doniV si emaN yM