Javaで文字列圧縮を実装する方法

public static void zipStr(String str) {
		char[] c = str.toCharArray();
		int index = 0;
		int num = 1;
		int len = c.length;
		while (index < len - 1) {
			while (c[index] == c[index + 1]) {
				num++;
				index++;
				if (index >= len - 1) {
					break;
				}
			}
			System.out.print(c[index]);
			System.out.print(num);
			num = 1;
			index++;
		}
	}

public static HashMap fun1(String str) {
		HashMap<Character, Integer> map = new HashMap<Character, Integer>();
		char[] c = str.toCharArray();
		for (int i = 0; i < c.length; i++) {
			Integer count = map.get(c[i]);//此处的count的类型一定要为Integer，如果为int类型，则count值为0
			if (!map.containsKey(c[i])) {
				map.put(c[i], 1);
			} else {
				map.put(c[i], count + 1);
			}
		}
		return map;
	}