Java: Reverses the words in a string that have odd lengths

Last update on May 21 2025 12:48:55 (UTC/GMT +8 hours)

109. Reverse Odd-Length Words

Write a Java program that reverses all odd-length words in a string.

Visual Presentation:

Sample Data:

(“Check two consecutive identical letters in a given string”) -> “kcehC owt evitucesnoc lacitnedi srettel in a nevig string”
("Create a Date object using the Calendar class") -> “Create a Date object gnisu eht Calendar ssalc”

Sample Solution:

Java Code:

public class Main {
    public static void main(String[] args) {
        // Define a string 'text' with a sentence
        String text = "Check two consecutive identical letters in a given string";
        System.out.println("Original text: " + text); // Display the original text
        
        // Reverse the words with odd lengths in the string and display the modified string
        System.out.println("\nReverses the words in the string that have odd lengths:\n" + test(text));
        
        // Change the value of 'text' to another sentence
        text = "Create a Date object using the Calendar class";
        System.out.println("\nOriginal text: " + text); // Display the original text
        
        // Reverse the words with odd lengths in the string and display the modified string
        System.out.println("\nReverses the words in the string that have odd lengths:\n" + test(text));
    }

    // Method to reverse words with odd lengths in a string
    public static String test(String str) {
        // Split the string into words using space as a delimiter
        String[] str_words = str.split(" ");
        
        // Iterate through each word in the array
        for (int i = 0; i < str_words.length; i++) {
            // Check if the length of the word is odd
            if (str_words[i].length() % 2 != 0) {
                // Reverse the word using StringBuilder and update the array element
                StringBuilder reverser = new StringBuilder(str_words[i]);
                str_words[i] = reverser.reverse().toString();
            }
        }
        
        // Join the modified words to form a string and return the result
        return String.join(" ", str_words);
    }
}

Sample Output:

Original text: Check two consecutive identical letters in a given string

Reverses the words in the string that have odd lengths:
kcehC owt evitucesnoc lacitnedi srettel in a nevig string

Original text: Create a Date object using the Calendar class

Reverses the words in the string that have odd lengths:
Create a Date object gnisu eht Calendar ssalc

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to reverse only the words that have an odd number of characters in a sentence.
• Write a Java program to process a string and invert the letters of each odd-length word.
• Write a Java program to split a sentence into words, reverse those with odd lengths, and reassemble the sentence.
• Write a Java program to iterate over words in a string and reverse the ones with an odd character count.

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