有字符数组a[n],将数组元素顺序颠倒、找出出现频率最高的数组成员

    /**
     * 将字符数组逆序
     */
    public static void reverseChar(char[] a, int left , int right){
        if (left >= right)
            return;
        char temp;
        temp = a[left];
        a[left] = a[right];
        a[right] = temp;
        reverseChar(a, ++left, --right);
    }

    /**
     * 找出出现频率最高的数组成员
     */
    private static Character getMember(char[] b) {
        HashMap<Character, Integer> hm = new HashMap();
        int maxCount = 0;
        Character maxCountElement = b[0];
        for (int i = 0; i < b.length; i++) {
            Character key = new Character(b[i]);
            if (hm.containsKey(key)) {
                Integer count = hm.get(key);
                hm.put(key, count + 1);
                if (count > maxCount){
                    maxCount = count;
                    maxCountElement = key;
                }
            } else {
                hm.put(key, 1);
            }
        }
        return maxCountElement;
    }

    public static void main(String[] args) {
        char[] a = {'a', 'b', 'b', 'c'};
        reverseChar(a, 0, a.length - 1);
        System.out.println(a);

        Character member = getMember(a);
        System.out.println(member);
    }