Java字符串压缩（两种压缩方式）

    public static String doDepressTwo(String str) {
        if ("".equals(str)) return str;
        char[] chars = str.toCharArray();
        HashMap<Character, Integer> map = new HashMap<>();
        for (char c : chars) {
            if (map.containsKey(c)) {
              //如果存在该键，则只需要value+1
                Integer integer = map.get(c);
                map.put(c, ++integer);
            } else {
              //如果不存在该键，就直接放入，value为1
                map.put(c, 1);
            }
        }
        StringBuilder sb = new StringBuilder();
        map.entrySet().forEach(entry -> {
          //将key和value拼接到sb
            sb.append(entry.getKey()).append(entry.getValue());
        });
        return sb.toString();
    }

    public static String doDepress(String str) {
        //字符串为空直接返回
        if ("".equals(str)) return str;
        StringBuilder buffer = new StringBuilder();
        //用第n个字符去和第n+1个字符对比
        char c = str.charAt(0);
        //记录字符出现次数，默认为1
        int repeat = 1;
        for (int i = 1; i < str.length(); i++) {
            if (c == str.charAt(i)) {
                //如果第n个字符和第n+1个字符相等，则出现次数+1
                repeat++;
            } else {
                //如果第n个字符和第n+1个字符不相等，则拼接在字符串后面
                buffer.append(c).append(repeat);
                //拼接完后重置当前字符串
                c = str.charAt(i);
                //重置字符出现次数
                repeat = 1;
            }
        }
        //最后一组在for循环里是没有拼接的
        return buffer.append(c).append(repeat).toString();
    }

    public static void main(String[] args) {
        log.info("唱跳rap的蔡徐鸡========>{}", doDepress("唱跳rap的蔡徐鸡"));
        log.info("唱跳raaaaap的的蔡徐鸡==>{}", doDepress("唱跳raaaaap的的蔡徐鸡"));
        log.info("aabcccccaaa=========>{}", doDepress("aabcccccaaa"));
        log.info("唱跳rap的蔡徐鸡========>{}", doDepressTwo("唱跳rap的蔡徐鸡"));
        log.info("唱跳raaaaap的的蔡徐鸡==>{}", doDepressTwo("唱跳raaaaap的的蔡徐鸡"));
        log.info("aabcccccaaa=========>{}", doDepressTwo("aabcccccaaa"));
    }