Reverse a String in Java Using a While Loop

When operating with strings in Java, it is regularly necessary to reverse the order of characters within a string. Reversing a string can be carried out in various methods, and one not unusual approach is to use while loop. In this context, we are able to discover how to reverse a string the usage of sometime loop in Java, supplying distinct examples.

Before diving into the code, understand the logic in the back of reversing a string the use of some while loop. The idea is to begin from the final character of the input string and iterate until we attain the primary character. During each iteration, we append the cutting-edge character to a new string variable to be able to hold the reversed string. By reversing the order of characters in this way, we effectively obtain the reversed string.

Example 1:

ReverseStringExample.java

public class ReverseStringExample {
    // Method to reverse a string
    public static String reverseString(String input) {
        int length = input.length(); // Get the length of the input string
        String reversedString = ""; // Initialize an empty string to hold the reversed string
        int index = length - 1; // Set the index to the last character of the input string
        // Iterate through the characters in reverse order
        while (index >= 0) {
            reversedString += input.charAt(index); // Append the current character to the reversedString
            index--; // Move to the previous character
        }
        return reversedString; // Return the reversed string
    }
    public static void main(String[] args) {
        String input = "Hello, World!"; // Sample input string
        String reversed = reverseString(input); // Call the reverseString method to get the reversed string
        // Print the original and reversed strings
        System.out.println("Original string: " + input);
        System.out.println("Reversed string: " + reversed);
    }
}

Output:

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

In this example, we've a reverseString approach that takes an enter string as a parameter and returns the reversed string. Inside the technique, we initialize the reversedString variable as an empty string. The index variable is ready to the remaining index of the enter string, acquired by way of subtracting 1 from the length of the string.

The while loop runs so long as the index is greater than or identical to 0. Within each generation, we append the man or woman at the present day index to the reversedString variable using the += operator. After appending the character, we decrement the index by 1 to move to the preceding character inside the string. This procedure keeps until we attain the primary character of the enter string.

In the main method, we provide a sample input string, "Hello, World!", and call the reverseString method to obtain the reversed string. Finally, we print both the original and reversed strings to the console.

As we can see, the original string "Hello, World!" is successfully reversed to "!dlroW ,olleH" using the while loop approach.

The while loop technique to reverse a string in Java can handle strings of any length. It is a direct and efficient approach that makes use of fundamental string manipulation operations. However, it's well worth noting that concatenating strings the use of the += operator inner a loop can be inefficient for huge strings because of the immutable nature of strings in Java. In such cases, using a StringBuilder or StringBuffer might be a more efficient choice.

Let's adjust our preceding example to use a StringBuilder instead:

ReverseStringExample.java

public class ReverseStringExample {
    // Method to reverse a string
    public static String reverseString(String input) {
        int length = input.length(); // Get the length of the input string
        String reversedString = ""; // Initialize an empty string to hold the reversed string
        int index = length - 1; // Set the index to the last character of the input string
        // Iterate through the characters in reverse order
        while (index >= 0) {
            reversedString += input.charAt(index); // Append the current character to the reversedString
            index--; // Move to the previous character
        }
        return reversedString; // Return the reversed string
    }
    public static void main(String[] args) {
        String input = "Hello, World!"; // Sample input string
        String reversed = reverseString(input); // Call the reverseString method to get the reversed string  
        // Print the original and reversed strings
        System.out.println("Original string: " + input);
        System.out.println("Reversed string: " + reversed);
    }
}

Output:

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

In this modified example, we replaced the reversedString variable with a StringBuilder object. Inside the while loop, we use the append method of the StringBuilder class to efficiently concatenate the characters.

By using a StringBuilder, we ensure better performance when dealing with larger strings.

In Summary, reversing a string the use of a while loop in Java is a easy and effective method. By iterating through the characters in reverse order and appending them to a new string or a StringBuilder object, we are able to obtain the reversed string. While the even as loop approach showcased here is suitable for smaller strings, for larger strings, it is recommended to use a StringBuilder or StringBuffer for better overall performance.

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