Wrapper's parseXXX() for signed binary misunderstanding
api-design, binary, java, parsing
Solution
Am I wrong about this?
Yes. The Javadoc says nothing about 2's-complement. Indeed, it explicitly states how it recognises negative values (i.e. a `-` prefix, so effectively "human-readable" sign-magnitude).
Think about it another way. If `parseByte` interpreted radix-2 as 2's-complement, what would you want it to do for radix-10 (or indeed, any other radix)? For consistency, it would have to be 10's-complement, which would be inconvenient, I can assure you!
Problem
Let's take `Byte.parseByte()` as an example as one of the wrappers' `parseXXX()`. From `parseByte(String s, int radix)'s JavaDoc`: Parses the string argument as a signed byte in the radix specified by the second argument. But that's not quite true if `radix = 2`. In other words, the binary literal of `-127` is `10000000`: ``` byte b = (byte) 0b10000000; ``` So the following should be true: ``` byte b = Byte.parseByte("10000000", 2); ``` but unfortunately, it throws `NumberFormatException`, and instead I have to do it as follows: ``` byte b = Byte.parseByte("-111111", 2); ``` where `parseByte()` parses the binary string as a sign-magnitude (the sign and the magnitude), where it should parse as a signed binary (2's complement, i.e. MSB is the sign-bit). Am I wrong about this?