Fast exponent Java

gistfile1.txt

    public static long pow2(long a, long b) {
        long re = 1;
        while (b > 0) {
            if ((b & 1) == 1) {
                re *= a;        
            }
            b >>= 1;
            a *= a; 
        }
        return re;
    }
    
       public static long pow1(long a, long b) {
        long re = 1;
        while (b-- > 0) {
            re *= a;
        }
        return re;
    }