我怎样才能把一个int到Java的三个字节？ [英] How can I turn an int into three bytes in Java?

问题描述

我想转换一个 INT 成三个字节重新presenting了 INT （大端）。

I am trying to convert an int into three bytes representing that int (big endian).

我敢肯定它是与逐位与和位转移。但我不知道如何去这样做。

I'm sure it has something to do with bit-wise and and bit shifting. But I have no idea how to go about doing it.

例如：

int myInt;

// some code

byte b1, b2 , b3; // b1 is most significant, then b2 then b3.

*注意，我知道一个int是4字节和三个字节的上/​​下溢的机会。

*Note, I am aware that an int is 4 bytes and the three bytes have a chance of over/underflowing.

推荐答案

要获得最显著字节：

b3 = myInt & 0xFF;

第二最小显著字节：

The 2nd least significant byte:

b2 = (myInt >> 8) & 0xFF;

和第三至少显著字节：

b1 = (myInt >> 16) & 0xFF;

说明：

按位与运算为0xFF的值（11111111二进制）将在该号码返回至少显著8位（位0到7）。移位数到右边的8倍把位8到15进位位置0到7，以便与运算为0xFF将返回第二个字节。同样地，移数到右边16次把位16到23为位位置0到7所以AND运算为0xFF返回第三个字节。

Bitwise ANDing a value with 0xFF (11111111 in binary) will return the least significant 8 bits (bits 0 to 7) in that number. Shifting the number to the right 8 times puts bits 8 to 15 into bit positions 0 to 7 so ANDing with 0xFF will return the second byte. Similarly, shifting the number to the right 16 times puts bits 16 to 23 into bit positions 0 to 7 so ANDing with 0xFF returns the 3rd byte.

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