What is the best way to extract bit fields in Java prior to 1.7? I know I can use bitwise operations, but isn't it better methods?
I need to extract the portion of bit array with endianness control as integer values.
Asked
Active
Viewed 353 times
0
-
2Why does endianness affect anything? – Oliver Charlesworth Jun 26 '12 at 16:13
-
@Suzan Cioc: Java handles the endianness when extracting bit fields. – Chris Dargis Jun 26 '12 at 16:14
-
Normally the endianess is in reading/writing the data from a Stream or Channel. Extracting the bits is a seperate step. bitwise operations are the simplest way to operate on bits (thus the name) – Peter Lawrey Jun 26 '12 at 16:17
-
@Oli because. If I know that field is from bits number 10 and 11, I can't extract them without knowing endianness. – Suzan Cioc Jun 26 '12 at 16:18
-
@Peter how to set endianness when reading? – Suzan Cioc Jun 26 '12 at 16:19
-
I would use `ByteBuffer.order(ByteOrder)` and then get the 10th and 11th bit. – Peter Lawrey Jun 26 '12 at 16:24
-
@Peter, how to get bits from `ByteBuffer`? – Suzan Cioc Jun 26 '12 at 16:25
-
You get an `int` value using `getInt()` You have to get the value first, then extract the bits. – Peter Lawrey Jun 26 '12 at 16:30
-
3@SuzanCioc: Bit #10 is always `(x & (1 << 10))`. The only place endianness matters is if `x` has come from some external interface (like a network packet or something). But if that's the case, you should deal with the endianness when you read the data in, rather than every time you need to extract information from it. – Oliver Charlesworth Jun 26 '12 at 16:37