位运算有关

计算一个整数中位为1的位数：

public class BitCount {
	public static int bitCount(int x) {
		if(x == 0) {
			return 0;
		}
		
		if(x < 0) {
			x = -x;
		}
		
		int count = 1;
		
		while((x &= (x - 1)) != 0) {
			count++;
		}
		
		return count;
	}

	public static void main(String[] args) {
		System.out.println(bitCount(0));
		System.out.println(bitCount(1));
		System.out.println(bitCount(5));
		System.out.println(bitCount(7));
		System.out.println(bitCount(-9));
	}
}

不借住额外存储空间交换两个整数的值：

int a = 3, b = 5;
		
System.out.printf("a = %d, b = %d\n", a, b);
		
a = a + b;
b = a - b;
a = a - b;
		
System.out.printf("a = %d, b = %d\n", a, b);

a = a ^ b;
b = a ^ b;
a = a ^ b;
		
System.out.printf("a = %d, b = %d\n", a, b);