Find the Longest Word in a Sentence in Java — Definition, Examples and Program

Find the Longest Word in a Sentence in Java

Finding the longest word in a sentence means identifying the word that contains the maximum number of characters.

This is a very common string problem in interviews and helps build a strong understanding of loops and string traversal.

Understanding the Problem

Given a sentence, we need to:

• Extract each word from the sentence.
• Compare its length with the previously stored longest word.
• Update the longest word when a bigger one is found.

Example 1

Input: Java programming is powerful

Output: programming

Example 2

Input: Find the longest word

Output: longest

Logic Explanation

1. Traverse the sentence character by character.
2. Store characters of the current word.
3. When a space is encountered, compare word length.
4. Update the longest word if required.
5. Check the last word after the loop ends.

Java Program to Find the Longest Word

import java.util.Scanner;

public class LongestWordInSentence {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a sentence: ");
        String str = sc.nextLine();

        String word = "";
        String longestWord = "";

        for (int i = 0; i < str.length(); i++) {

            char ch = str.charAt(i);

            if (ch != ' ') {
                word = word + ch;
            } else {
                if (word.length() > longestWord.length()) {
                    longestWord = word;
                }
                word = "";
            }
        }

        // Check last word
        if (word.length() > longestWord.length()) {
            longestWord = word;
        }

        System.out.println("Longest word: " + longestWord);
    }
}

Sample Output

Enter a sentence: Java programming is powerful
Longest word: programming

Important Notes

• If multiple words have the same maximum length, the first one is returned.
• No use of split() method.
• Works for normal space-separated sentences.

Practice Challenges

1. Modify the program to find all longest words.
2. Ignore punctuation marks while finding the longest word.
3. Also print the length of the longest word.

This problem is excellent for mastering string traversal and conditional logic in Java.