CONVERSIONS AND PROMOTIONS

Narrowing Primitive Conversions

5.1.3

resulting floating point value will be a correctly rounded version of the integer

value, using IEEE 754 round to nearest mode ( 4.2.4).

A widening conversion of a signed integer value to an integral type

T

 simply

sign extends the two's complement representation of the integer value to fill the

wider format. A widening conversion of a character to an integral type

T

 zero 

extends the representation of the character value to fill the wider format.

Despite the fact that loss of precision may occur, widening conversions

among primitive types never result in a run time exception ( 11).

Here is an example of a widening conversion that loses precision:

class Test {

public static void main(String[] args) {

int big = 1234567890;

float approx = big;

System.out.println(big   (int)approx);

}

}

which prints:

 46

thus indicating that information was lost during the conversion from type

int

 to

type

float

 because values of type

float

 are not precise to nine significant digits.

5.1.3   Narrowing Primitive Conversions

The following 23 specific conversions on primitive types are called the

narrowing

primitive conversions

:

byte

to

char

short

to

byte

 or

char

char

to

byte

 or

short

int

to

byte

,

short

, or

char

long

to

byte

,

short

,

char

, or

int

float

to

byte

,

short

,

char

,

int

, or

long

double

to

byte

,

short

,

char

,

int

,

long

, or

float

Narrowing conversions may lose information about the overall magnitude of a

numeric value and may also lose precision.

A narrowing conversion of a signed integer to an integral type

T

 simply dis 

cards all but the

n

lowest order bits, where

n

is the number of bits used to repre 

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