Lexical Structure - The Java Language Specification - page 28

f F d D
HexadecimalFloatingPointLiteral:
HexSignificand BinaryExponent FloatTypeSuffix opt
HexSignificand:
HexNumeral
HexNumeral .
0 x HexDigits opt . HexDigits
0 X HexDigits opt . HexDigits
BinaryExponent:
BinaryExponentIndicator SignedInteger
BinaryExponentIndicator:one of
p P
A floating-point literal is of type float if it is suffixed with an ASCII letter F or f ; otherwise
its type is double and it can optionally be suffixed with an ASCII letter D or d (§ 4.2.3 ).
The elements of the types float and double are those values that can be represented using the
IEEE 754 32-bit single-precision and 64-bit double-precision binary floating-point formats,
respectively.
The details of proper input conversion from a Unicode string representation of a
floating-point number to the internal IEEE 754 binary floating-point representation
are described for the methods valueOf of class Float and class Double of the package
java.lang .
The largest positive finite literal of type float is 3.4028235e38f .
The smallest positive finite non-zero literal of type float is 1.40e-45f .
The largest positive finite literal of type double is 1.7976931348623157e308 . The smallest pos-
itive finite non-zero literal of type double is 4.9e-324 .
It is a compile-time error if a non-zero floating-point literal is too large, so that on rounded
conversion to its internal representation, it becomes an IEEE 754 infinity.
A program can represent infinities without producing a compile-time error by using con-
stant expressions such as 1f/0f or -1d/0d or by using the predefined constants
POSITIVE_INFINITY and NEGATIVE_INFINITY of the classes Float and Double .
It is a compile-time error if a non-zero floating-point literal is too small, so that, on rounded
conversion to its internal representation, it becomes a zero.