This method returns the HashMap of words and their respective counts.

getWordCountMap.txt

		Map<String, Integer> wordCountMap = new HashMap<String, Integer>();
		String[] inputFilePathArray = new String[4];
		inputFilePathArray[0] = "C:\\input1.txt";
		inputFilePathArray[1] = "C:\\input2.txt";
		inputFilePathArray[2] = "C:\\input3.txt";
		inputFilePathArray[3] = "C:\\input4.txt";
		for (String inputFilePath : inputFilePathArray) {
			BufferedReader br = new BufferedReader(
					new FileReader(inputFilePath));
			String line = null, mapKey = null;
			String[] lineSplitter = null;
			int i = 0;
			while ((line = br.readLine()) != null) {
				lineSplitter = line.split(" ");
				for (i = 0; i < lineSplitter.length; i++) {
					mapKey = lineSplitter[i].replaceAll("[\\.\\',\\?]", "");
					if (!(stopWordsList.contains(mapKey))
							&& mapKey.length() > 3) {
						if (wordCountMap.containsKey(mapKey))
							wordCountMap.put(mapKey,
									wordCountMap.get(mapKey) + 1);
						else
							wordCountMap.put(mapKey, 1);
					}
				}
			}
			br.close();
		}
		LinkedHashMap<String, Integer> sortedWordCountMap = sortHashMapByValues(wordCountMap);
		System.out.println("***TOP 10 MOST USED WORDS***");
		int count = 0;
		for (Entry<String, Integer> entry : sortedWordCountMap.entrySet()) {
			if (count < 10)
				System.out.println(entry.getKey() + " - " + entry.getValue());
			count++;
		}