WordCounter\Utils.java

package com.ourOffice.utils;

import java.io.FileWriter;
import java.io.IOException;
import java.util.HashMap;

public class Utils {
	/**
	 * This method is used to extract the file extension
	 * 
	 * @param fileName
	 *            input file name whose extension needs to be extracted
	 * @return
	 */
	public static String getFileExtension(String fileName) {
		String extension = null;
		int i = fileName.lastIndexOf('.');
		if (i > 0) {
			extension = fileName.substring(i + 1);
		}
		return extension;
	}

	/**
	 * This method is used to extract the file name without the extension
	 * 
	 * @param fileName
	 *            input file name has to be extracted
	 * @return
	 */
	public static String getFileNameWithoutExtension(String fileName) {
		String fileNameAlone = null;
		int i = fileName.lastIndexOf('.');
		if (i > 0) {
			fileNameAlone = fileName.substring(0, i);
		}
		return fileNameAlone;
	}

	/**
	 * This method is used for generating the csv file
	 * 
	 * @param fileName
	 *            Name of the output csv file
	 * @param hMap
	 *            HashMap containing words and count
	 * @param totalWordsCounter
	 *            total words counter in a file
	 */
	public static void generateCsvFile(String fileName, HashMap<String, Integer> hMap, int totalWordsCounter) {
		try (FileWriter writer = new FileWriter(fileName, false);) {
			writer.append("Word");
			writer.append(',');
			writer.append("Doc Frequency");
			writer.append(',');
			writer.append("Doc Frequency/1000");
			writer.append('\n');

			for (String key : hMap.keySet()) {
				String value = hMap.get(key).toString();

				double valueDouble = Double.parseDouble(value);
				double totalWordsCounterDouble = totalWordsCounter;

				writer.append(key);
				writer.append(',');
				writer.append(value);
				writer.append(',');
				// If number of occurrences / Total Words is needed, uncomment
				// the next line and comment the one after next line.
				// writer.append(value + "/" + totalWordsCounter);
				writer.append(Double.valueOf(valueDouble / totalWordsCounterDouble).toString());
				writer.append('\n');

			}
			writer.flush();
			writer.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}