实现将金币按照千为单位，以＂，＂分割的算法

实现将金币按照千为单位，以＂，＂分割的算法

class MultixCoins {
	public static void main(String[] args) {
		 System.out.println(adjustCoins(1222000000, '-'));

        adjustCoin(15203, ',');

        System.out.println(sb.toString());
	}
	// 使用递归思想实现
	private static StringBuilder sb = new StringBuilder();

    private static String adjustCoin(long coin, char split) {
        if (coin <= 0) {
            throw new IllegalArgumentException("coin must > 0");
        }
        if (coin <= 1000) {
            sb.append(coin);
            return sb.toString();
        }
        long remainder = coin % 1000;
        String mulStr = "";
        if (remainder >= 100) {
            mulStr = split + "" + remainder;
        } else if (remainder >= 10) {
            mulStr = split + "0" + remainder;
        } else {
            mulStr = split + "00" + remainder;
        }
        long realCoin = coin / 1000;
        adjustCoin(realCoin, split);
        sb.append(mulStr);
        return sb.toString();
    }
//　使用字符数组实现
    private static String adjustCoins(long coin, char split) {
        if (coin <= 0) {
            throw new IllegalArgumentException("coin must > 0");
        }
        if (coin <= 1000) {
            return "" + coin;
        }
        char[] chars = String.valueOf(coin).toCharArray();
        int replaceNum = chars.length / 3;
        char[] result = new char[chars.length + replaceNum-1];
        int resultLength = result.length - 1;
        for (int i = chars.length - 1; i >= 0; i--) {
            if (replaceNum > 0) {
                result[resultLength--] = chars[i--];
                result[resultLength--] = chars[i--];
                result[resultLength--] = chars[i];
                if (i != 0) {
                    result[resultLength--] = split;
                }
                replaceNum--;
            } else {
                result[resultLength--] = chars[i];
            }
        }
        return new String(result);
    }
}