Substring counter

SubstringCounter.java

import java.util.HashMap;
import java.util.Map;

public class HelloWorld {

	public static void main(String[] args) {

		String str = "this is what this is";
		
		System.out.println(str);
		
		Map<String, Integer> map = findOccurences(str, 3);
		
		for (String string : map.keySet()) {
		
			System.out.println(string + " : " + map.get(string));
		}
	}

	public static Map<String, Integer> findOccurences(String str, int count) {

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

		String sub;

		int stringLen = str.length() - (count - 1);

		for (int i = 0; i < stringLen; i++) {

			sub = str.substring(i, i + count);

			if (map.containsKey(sub)) {

				int counter = map.get(sub);
				counter++;

				map.put(sub, counter);
				counter = 0;

			} else {

				map.put(sub, 1);
			}
		}

		return map;
	}
}