Map and Map.Entry interface will be used as the Map interface maps unique keys to values. A key is an object that is used to retrieve a value at a later date. The Map.Entry interface enables you to work with a map entry. Also, we will use the HashMap class to store items in “key/value” pairs and access them by an index of another type.
Illustration:
Suppose the content of the sample text file is as follows:
Input: A text file containing sequence of arbitrary words
“How to count the number of occurrence of each word? How to count number or each word in string. Calculating frequency of each word in a sentence in java.”
Output: List of words that have the maximum occurrence
in = 3 each = 3 of = 3 to = 3
Implementation: Sample file input image is as follows:
Example
Java
// Java Program to Find the// Most Repeated Word in a Text File// Importing File classesimport java.io.File;import java.io.FileNotFoundException;// Importing Map and HashMap class from// java.util packageimport java.util.HashMap;import java.util.Map;import java.util.Map.Entry;// Importing Scanner class to// take input from the userimport java.util.Scanner;// Class// To find maximum occurrencespublic class GFG { // Method 1 - getWords() // Reading out words from the file and // mapping key value pair corresponding to // each different word static void getWords(String fileName, Map<String, Integer> words) throws FileNotFoundException { // Creating a Scanner class object Scanner file = new Scanner(new File(fileName)); // Condition check using hasNext() method which // holds true till there is word being read from the // file. // As the end of file content,condition violates while (file.hasNext()) { // Reading word using next() method String word = file.next(); // Frequency count variable Integer count = words.get(word); // If the same word is repeating if (count != null) { // Incrementing corresponding count by unity // every time it repeats // while reading from the file count++; } else // If word never occurred after occurring // once, set count as unity count = 1; words.put(word, count); } // Close the file and free up the resources file.close(); } // Method 2 - getMaxOccurrence() // To get maximum occurred Word static int getMaxOccurrence(Map<String, Integer> words) { // Initially set maximum count as unity int max = 1; // Iterating over above Map using for-each loop for (Entry<String, Integer> word : words.entrySet()) { // Condition check // Update current max value with the value // exceeding unity in Map while traversing if (word.getValue() > max) { max = word.getValue(); } } // Return the maximum value from the Map return max; } // Method 3 // Main driver method public static void main(String[] args) throws FileNotFoundException { // Creating an object of type Map // Declaring object of String and Integer types Map<String, Integer> words = new HashMap<String, Integer>(); // Retrieving the path as parameter to Method1() // above to get the file to be read getWords("C:\\Users\\dell\\sample.txt", words); // Variable holding the maximum // repeated word count in a file int max = getMaxOccurrence(words); // Traversing using for each loop // Creating a set out of same elements // contained in a HashMap for (Entry<String, Integer> word : words.entrySet()) { // Comparing values using geValue() method if (word.getValue() == max) { // Print and display word-count pair System.out.println(word); } } } |
Output:
Time Complexity: O(n)
Auxiliary Space: O(n)
