Java StringBuilder reverse() Method

The StringBuilder.reverse() method in Java is used to reverse the sequence of characters in a StringBuilder object.

Table of Contents

  1. Introduction
  2. reverse Method Syntax
  3. Examples
    • Reversing a StringBuilder
    • Reversing Palindromes
  4. Real-World Use Case
  5. Conclusion

Introduction

The StringBuilder.reverse() method is a member of the StringBuilder class in Java. It allows you to reverse the order of characters in the StringBuilder object, which can be useful for various applications, such as creating palindromes, reversing input strings, or solving specific algorithmic problems.

reverse() Method Syntax

The syntax for the reverse method is as follows:

public StringBuilder reverse()

This method does not take any parameters and returns the same StringBuilder object with the characters reversed.

Examples

Reversing a StringBuilder

The reverse method can be used to reverse the sequence of characters in a StringBuilder.

Example

public class StringBuilderReverseExample {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder("Hello, World!");

        // Reverse the characters in the StringBuilder
        sb.reverse();

        // Print the result
        System.out.println("Reversed StringBuilder: " + sb.toString());
    }
}

Output:

Reversed StringBuilder: !dlroW ,olleH

Reversing Palindromes

Reversing a palindrome results in the same sequence of characters, demonstrating the property of palindromes.

Example

public class StringBuilderPalindromeExample {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder("madam");

        // Reverse the characters in the StringBuilder
        sb.reverse();

        // Print the result
        System.out.println("Reversed StringBuilder (palindrome): " + sb.toString());
    }
}

Output:

Reversed StringBuilder (palindrome): madam

Real-World Use Case

Example: Checking if a String is a Palindrome

In a real-world scenario, you might need to check if a given string is a palindrome. Using the reverse method, you can easily compare the original string with its reversed version.

Example Code

public class PalindromeChecker {
    public static void main(String[] args) {
        String input = "racecar";

        if (isPalindrome(input)) {
            System.out.println("The string is a palindrome.");
        } else {
            System.out.println("The string is not a palindrome.");
        }
    }

    public static boolean isPalindrome(String str) {
        StringBuilder sb = new StringBuilder(str);
        String reversedStr = sb.reverse().toString();
        return str.equals(reversedStr);
    }
}

Output:

The string is a palindrome.

Conclusion

The StringBuilder.reverse() method in Java is used for reversing the sequence of characters in a StringBuilder object. By understanding how to use this method, you can efficiently manipulate strings and solve various problems that require reversed sequences. Whether you need to reverse a string, check for palindromes, or perform other character sequence manipulations, the reverse method provides a reliable solution for these tasks.

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