Java 使用封装类计算模数除以2的幂数

在Java中，你可以使用Wrapper类的toBinaryString()方法来获得一个数字的二进制字符串表示，并获得从(str.length()-k )到最后的子串。然后通过使用Integer.parseInt()，你可以将这个二进制子串转换为数字，也就是余数。下面是一个Java程序来证明这一点。

// Java program to Compute modulus
// division by a power-of-2-number
  
class Test
{
    // Driver method
    public static void main(String[] args) 
    {
        int num = 15;
          
        int two_power1 = 1;
        int two_power2 = 2;
        int two_power3 = 3;
          
        String binary = Integer.toBinaryString(num);
        int len = binary.length();
          
        String rem1 = binary.substring(len-two_power1);
        String rem2 = binary.substring(len-two_power2);
        String rem3 = binary.substring(len-two_power3);
          
        int reme1 = Integer.parseInt(rem1, 2);
        int reme2 = Integer.parseInt(rem2, 2);
        int reme3 = Integer.parseInt(rem3, 2);
          
        System.out.println(num + "%" + "2^(" + two_power1 + ") = " + reme1);
        System.out.println(num + "%" + "2^(" + two_power2 + ") = " + reme2);
        System.out.println(num + "%" + "2^(" + two_power3 + ") = " + reme3);
    }
}

输出:

15%2^(1) = 1
15%2^(2) = 3
15%2^(3) = 7