Data types

All types in Java (and as such Minecraft) are big-endian, that is, the most significant byte comes first. The majority of everyday computers are little endian, and using most programming languages will require converting big endian values to little endian.

Other than 'String' and 'Metadata', which are decoded with a custom function, these data formats are identical to those provided by the Java classes DataInputStream and DataOutputStream.

	Size	Range	Notes
byte	1	-128 to 127	Signed, two's complement
short	2	-32768 to 32767	Signed, two's complement
int	4	-2147483648 to 2147483647	Signed, two's complement
long	8	-9223372036854775808 to 9223372036854775807	Signed, two's complement
float	4	See this	Single-precision 32-bit IEEE 754 floating point
double	8	See this	Double-precision 64-bit IEEE 754 floating point
string	≥ 2 ≤ 240	N/A	UCS-2 string, big-endian. Prefixed by a short containing the length of the string in characters. UCS-2 consists of 16-bit words, each of which represent a Unicode code point between U+0000 and U+FFFF inclusive.
bool	1	0 or 1	Value can be either True (0x01) or False (0x00)
metadata	Varies	See this

Some data may be stored as an "absolute integer", which is a more precise kind of integer, and a less precise kind of double. The conversion from double to absolute integer is like so:

abs_int = (int)double * 32;

And back again:

double = (double)abs_int / 32;