Java: Find all of the longest word in a given dictionary

Last update on May 12 2025 13:11:08 (UTC/GMT +8 hours)

Longest Word in Dictionary

Write a Java program to find the longest words in a dictionary.

Example-1:
{
"cat",
"flag",
"green",
"country",
"w3resource"
}
Result: "w3resource"
Example-1:
{
"cat",
"dog",
"red",
"is",
"am"
}
Result: "cat", "dog", "red"

Pictorial Presentation:

Sample Solution:

Java Code:

import java.util.*;

public class Solution {
    // Function to find and return the longest words in the given dictionary
    static ArrayList longestWords(String[] dictionary) {
        ArrayList list = new ArrayList();
        int longest_length = 0;

        // Iterate through each word in the dictionary
        for (String str : dictionary) {
            int length = str.length();
            
            // Check if the current word is longer than the previously found longest word(s)
            if (length > longest_length) {
                longest_length = length;
                list.clear(); // Clear the list as a new longest word is found
            }
            
            // If the current word has the same length as the longest word(s), add it to the list
            if (length == longest_length) {
                list.add(str);
            }
        }
        return list; // Return the list of longest words
    }
    
    public static void main(String[] args) {
        // Sample dictionary containing words
        // String[] dict = {"cat", "flag", "green", "country", "w3resource"};
        String[] dict = {"cat", "dog", "red", "is", "am"};

        // Print the original dictionary and the longest word(s)
        System.out.println("Original dictionary: " + Arrays.toString(dict));
        System.out.println("Longest word(s) of the above dictionary: " + longestWords(dict));
    }		
}

Sample Output:

Original dictionary : [cat, dog, red, is, am]
Longest word(s) of the above dictionary: [cat, dog, red]

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to find the longest word in a dictionary that can be formed by deleting some characters of a given string.
• Write a Java program to return the longest word in a dictionary that contains all vowels at least once.
• Write a Java program to find the longest word that can be constructed using letters from a given set of characters.
• Write a Java program to find the longest word that is a palindrome in a given dictionary.

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