返回指定的 int 值的二进制补码表示形式中最低（“最右”）的为 1 的位后面的零位个数...

public static int numberOfTrailingZeros(int i) {

// HD, Figure 5-14

int y;

if (i == 0) return 32;

int n = 31;

y = i <<16; if (y != 0) { n = n -16; i = y; }

y = i << 8; if (y != 0) { n = n - 8; i = y; }

y = i << 4; if (y != 0) { n = n - 4; i = y; }

y = i << 2; if (y != 0) { n = n - 2; i = y; }

return n - ((i << 1) >>> 31);

}