The Floating-Point Types

Floating-point numbers are represented by the float and double data types.

Floating-point numbers conform to the IEEE 754-1985 binary floating-point standard. Table 2.14 shows the range of values for positive floating-point numbers, but these apply equally to negative floating-point numbers with the minus sign (-) as a prefix. Zero can be either 0.0 or -0.0. The range of values represented by the double data type is wider than that of the float data type.

Table 2.14 Range of Floating-Point Values

Since the size for representation is a finite number of bits, certain floating-point numbers can be represented only as approximations. For example, the value of the expression (1.0/3.0) is represented as an approximation due to the finite number of bits used to represent floating-point numbers.

The boolean Type

The data type boolean represents the two logical values denoted by the literals true and false (Table 2.15).

Table 2.15 Boolean Values

Data type	Width	True value literal	False value literal
boolean	Not applicable	true	false

Boolean values are results of all relational (p. 74), conditional (p. 80), and boolean (p. 78) logical operators.

Table 2.16 summarizes the pertinent facts about the primitive data types: their width or size, which indicates the number of bits required to store a primitive value; their range of legal values, which is specified by the minimum and maximum values permissible; and the name of the corresponding wrapper class (§8.3, p. 429).

Table 2.16 Summary of Primitive Data Types

Data type	Width (bits)	Minimum value, maximum value	Wrapper class
boolean	Not applicable	true, false	Boolean
byte	8	–27, 27 – 1	Byte
short	16	–215, 215 – 1	Short
char	16	0x0, 0xffff	Character
int	32	–231, 231 – 1	Integer
long	64	–263, 263 – 1	Long
float	32	±1.40129846432481707e-45f, ±3.402823476638528860e+38f	Float
double	64	±4.94065645841246544e-324, ±1.79769313486231570e+308	Double