Java中位运算相关测试

package com.dellyqiao;

import java.util.Arrays;

public class TestBinary {
	public static void main(String[] args) {
		System.out.println(51&5);
		System.out.println(51|5);
		System.out.println(51^5); //按位取值对比，不同为1，相同为0，可用来翻转某几位（1），用0保留原值
		//变量交换值 (a^a为0，b^b为0。而数字^0为原数字。所以
		//a^b为中间值，新b=中间值^b，新a=中间值^a)
		int a = 51;
		int b = 5;
		a=a^b;
		b=a^b;
		a=a^b;
		System.out.println(a + " " + b);
		
		System.out.println(~0 + " " + ~1); //取反，每一位取反
		System.out.println(2<<1); //左移。二进制位全部左移，左边二进制位丢弃，右边补0
		//若舍弃的高位不包含1，则每左移一位，相当于乘以2
		System.out.println(-14<<2);
		
		System.out.println(4>>2); //右移。正数左补0，负数左补1，右边丢弃。
		//每右移一位，相当于该数除以2。
		System.out.println(-14>>2);
		
		System.out.println(-14>>>2);//无符号右移。左补0，右丢弃
		
		System.out.println(Integer.toBinaryString(112)); //转二进制
		System.out.println(Integer.toHexString(112)); //转16进制
		System.out.println(Integer.toOctalString(112)); //转8进制
		
		System.out.println(Integer.parseInt("111001", 2)); //二进制转10进制
		System.out.println(Integer.parseInt("27", 8)); //八进制转十进制
		System.out.println(Integer.parseInt("1A", 16)); //16进制转十进制
		
		
		//int转为byte[]
		int id = 8143;
		byte[] arr = new byte[4];
		arr[0] = (byte)((int)(id >> 0*8) & 0xff);
		arr[1] = (byte)((int)(id >> 1*8) & 0xff);
		arr[2] = (byte)((int)(id >> 2*8) & 0xff);
		arr[3] = (byte)((int)(id >> 3*8) & 0xff);
		
		System.out.println(arr[0] +"," + arr[1] + "," + arr[2] + "," + arr[3]);
		
		
		//byte[]转为int
		int rs0 = (int)((arr[0] & 0xff) << 0*8);
		int rs1 = (int)((arr[1] & 0xff) << 1*8);
		int rs2 = (int)((arr[2] & 0xff) << 2*8);
		int rs3 = (int)((arr[3] & 0xff) << 3*8);
		System.out.println(rs0 + rs1 + rs2 + rs3);
		
		//字符串与字节
		String describe = "你好世界";
		byte[] barr = describe.getBytes();
		System.out.println(Arrays.toString(barr));
		String des = new String(barr);
		System.out.println(des);
		
	}
}