java.lang.Integer.toHexString(b[n] & 0XFF)中0XFF使用的必要性

byte[] b = {1,2,20,108};

String stmp = java.lang.Integer.toHexString(b[n] & 0XFF)

在32位的电脑中数字都是以32格式存放的，如果是一个byte(8位)类型的数字，他的高24位里面都是随机数字，低8位

才是实际的数据。java.lang.Integer.toHexString() 方法的参数是int(32位)类型，如果输入一个byte(8位)类型的数字，这个

方法会把这个数字的高24为也看作有效位，这就必然导致错误，使用& 0XFF操作，可以把高24位置0以避免这样错误

的发生

0xFF = 1111 1111　低8位为1，高位都为0

故 &0xFF 可将数字的高位都置为0，低8位不变

http://blog.csdn.net/guo_rui22/article/details/2826308

时间： 2024-12-17 16:28:15

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