Word Frequency Counter

Word Frequency Counter in Java

Task

Write a Java program to count the frequency of each word in a given sentence. The program should:

1. Take a sentence as input.

2. Split the sentence into individual words.

3. Count how many times each word appears.

4. Print each word along with its frequency.

Example

Input:

the quick brown fox jumps over the lazy dog

Output:

the : 2

quick : 1

brown : 1

fox : 1

jumps : 1

over : 1

lazy : 1

dog : 1

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Code

import java.util.HashMap;

import java.util.Map;

public class WordFrequencyCounter {

    public static void main(String[] args) {

        // Input sentence

        String sentence = "the quick brown fox jumps over the lazy dog";

        // Split the sentence into words (using space as delimiter)

        String[] words = sentence.split(" ");

        // Create a HashMap to store words and their counts

        Map<String, Integer> wordCount = new HashMap<>();

        // Loop through each word

        for (String word : words) {

            // If the word already exists in the map, increase its count

            // If not, put it in the map with count 1

            wordCount.put(word, wordCount.getOrDefault(word, 0) + 1);

        }

        // Print each word with its frequency

        for (Map.Entry<String, Integer> entry : wordCount.entrySet()) {

            System.out.println(entry.getKey() + " : " + entry.getValue());

        }

    }

}

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Explanation

1. Splitting the sentence

String[] words = sentence.split(" ");

The split(" ") function divides the sentence into words based on spaces.

2. Using HashMap to store counts

Map<String, Integer> wordCount = new HashMap<>();

A HashMap is used because it stores data as key-value pairs.

The key is the word, and the value is the count of how many times the word appears.

3. Counting word frequencies

wordCount.put(word, wordCount.getOrDefault(word, 0) + 1);

getOrDefault(word, 0) → checks if the word already exists in the map.

If yes, it gets its count; if not, it takes 0.

Then we add 1 to update the count.

4. Displaying results

for (Map.Entry<String, Integer> entry : wordCount.entrySet()) {

    System.out.println(entry.getKey() + " : " + entry.getValue());

}

entrySet() gives all key-value pairs from the map.

We print each word (key) and its frequency (value).

✅ This exercise helps you practice String manipulation, HashMap usage, and iteration over a Map in Java.