Carl's Hacking Notes

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== Java Numeric ======

[[:java|Java]] Supports common [[:numeric|Numeric]] types in the language, as well as less common ones in the standard library (JDK).  Except for `char`, all native integer types are signed.  By default all numbers extend the ''Number'' abstract class.


----


===== Signed 32 Bit Integer =====

Java's default numeric type, ''int'', is a signed, 32 bit, [[https://en.wikipedia.org/wiki/Two%27s_complement|Two's complement]] integer.   Overflow is well defined.  The Boxed class ''Integer'' contains utility methods for working with ''int''s.  Additional support methods are in the ''Math'' class.


===== Signed 64 Bit Integer =====

Java's large numeric type, ''long'', is a signed, 64 bit, Two's complement, integer.   Overflow is well defined.



===== Signed 8 Bit Integer =====

A ''byte'' is a signed, 8 bit, Two's Complement, integer.  Unlike most other languages, a ''byte'' is signed, making it somewhat unwieldy.  The range goes from [-128, 127].   The JVM stack language does not natively work with bytes, but instead uses integer opcodes to work with them.


===== Signed 16 Bit Integer =====

A ''short'' is a signed, 16 bit, Two's Complement integer.  This type is pretty uncommon in use.  Like ''byte'', it has no operators in the JVM stack language, so all manipulation is done with integer opcodes.



===== Unsigned 16 Bit Integer =====

The character type ''char'' serves as Java's 16 bit, unsigned integer.   Typically ''char''s are used in String operations, since Java originally was designed for the [[https://en.wikipedia.org/wiki/Universal_Coded_Character_Set|UCS-2]] code point set.  As Unicode grew in code points, a fixed sized character type became less usable.  For higher code point, Java stores surrogate pairs in ''char''s.  

A character is almost always used with Strings, but be careful when combining them with Strings.  For example '' 'a' + 'b' + "c" ''  will result in numerically combining ''a'' and ''b'' before concatenating it to the string.