Java Pocket Guide

Chapter 3. Fundamental Types

Fundamental types include the Java primitive types and their corresponding wrapper classes/reference types. Java 5.0 and beyond provide for automatic conversion between these primitive and reference types through autoboxing and unboxing; see the “Autoboxing and Unboxing” section, later in this chapter. Numeric promotion is applied to primitive types where appropriate.

Primitive Types

There are eight primitive types in Java; each is a reserved keyword. They describe variables that contain single values of the appropriate format and size; see Table 3-1. Primitive types are always the specified precision, regardless of the underlying hardware precisions (e.g., 32- or 64-bit).

Table 3-1. Primitive types

Type	Detail	Storage	Range
boolean	true or false	1 bit	Not applicable
char	Unicode character	2 bytes	\u0000 to \uFFFF
byte	integer	1 byte	–128 to 127
short	integer	2 bytes	–32768 to 32767
int	integer	4 bytes	–2147483648 to 2147483647
long	integer	8 bytes	–263 to 263 –1
float	floating point	4 bytes	1.4e–45 to 3.4e+38
double	floating point	8 bytes	5e–324 to 1.8e+308

Tip

Primitive types byte, short, int, long, float, and doubleare all signed. Type char is unsigned.

Literals for Primitive Types

All primitive types, except boolean, can accept character, decimal, hexadecimal, octal, and Unicode literal formats, as well as character escape sequences. Where appropriate, the literal value is automatically cast or converted. ...