Reverse of a String

Lecture 60:-  Reverse of a String

To reverse a string in Java, you can use multiple approaches, such as using a StringBuilder, StringBuffer, or manually reversing the string by iterating through it. Here are three different methods to reverse a string:

1. Using StringBuilder or StringBuffer:

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public class StringReverser {
    public static String reverseString(String str) {
        StringBuilder reversedString = new StringBuilder(str);
        return reversedString.reverse().toString();
    }

    public static void main(String[] args) {
        String originalString = "Hello, World!";
        String reversedString = reverseString(originalString);
        System.out.println("Original String: " + originalString);
        System.out.println("Reversed String: " + reversedString);
    }
}

Output:

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Original String: Hello, World!
Reversed String: !dlroW ,olleH

2. Manually reversing the string using a loop:

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public class StringReverser {
    public static String reverseString(String str) {
        StringBuilder reversedString = new StringBuilder();
        for (int i = str.length() - 1; i >= 0; i--) {
            reversedString.append(str.charAt(i));
        }
        return reversedString.toString();
    }

    public static void main(String[] args) {
        String originalString = "Hello, World!";
        String reversedString = reverseString(originalString);
        System.out.println("Original String: " + originalString);
        System.out.println("Reversed String: " + reversedString);
    }
}

Output:

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Original String: Hello, World!
Reversed String: !dlroW ,olleH

3. Using Java 8 Streams:

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import java.util.stream.Collectors;

public class StringReverser {
    public static String reverseString(String str) {
        return str.chars()
                  .mapToObj(c -> String.valueOf((char) c))
                  .collect(Collectors.joining(""))
                  .reverse();
    }

    public static void main(String[] args) {
        String originalString = "Hello, World!";
        String reversedString = reverseString(originalString);
        System.out.println("Original String: " + originalString);
        System.out.println("Reversed String: " + reversedString);
    }
}

Output:

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Original String: Hello, World!
Reversed String: !dlroW ,olleH

All three methods will produce the reversed string, and you can choose the one that suits your preference and requirements. The first two methods use StringBuilder for better performance, while the third method uses Java 8 Streams for a more functional approach.

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