Java位操作:替换十六进制的半字节 [英] Java Bit Operations: replacing nibble of hex
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问题描述
我必须为家庭作业分配这段代码,但我什至不知道从哪里开始.这是我必须编写的方法的javadoc.
I have to write this code for a homework assignment but I don't even know where to start. Here is the javadoc to the method I have to write.
/**
* Sets a 4-bit nibble in an int
* Ints are made of eight bytes, numbered like so: 7777 6666 5555 4444 3333 2222 1111 0000
*
* For a graphical representation of this:
* 1 1 1 1 1 1
* 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Nibble3|Nibble2|Nibble1|Nibble0|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* Examples:
* setNibble(0xAAA5, 0x1, 0) //=> 0xAAA1
* setNibble(0x56B2, 0xF, 3) //=> 0xF6B2
*
* @param num int that will be modified
* @param nibble nibble to insert into the integer
* @param which determines which nibble gets modified - 0 for least significant nibble
*
* @return the modified int
*/
这就是我所拥有的.我已经将其与javadoc中的第一个示例一起使用,但是我知道这并不适用于所有情况.尤其是int其中!= 0;
Here is what I have. I've got it to work with the first example in the javadoc, But I know this does not hold true for all cases. Especially when int which != 0;
public static int setNibble(int num, int nibble, int which)
{
int newNibble = (num >> 4);
newNibble = (newNibble << 4) | nibble;
return newNibble;
}
我应该使用班次吗?有人告诉我可以在一行代码中执行此方法. 感谢您对高级的帮助!
Should I be using shifts or not? I was told I could do this method in one line of code. Thanks for the help in advanced!
推荐答案
我建议您;
- 通过构造掩码并使用
&
提取要保留的位
- 将要添加的位左移
<<
- 按位或将它们组合起来
- extract the bits you want to keep by constructing a mask and using
&
- place the bits to want to add into the right position with left shift
<<
- combine them with bitwise OR
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