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Class ExactConversionsSupport

java.lang.Object

java.lang.runtime.ExactConversionsSupport

public final class ExactConversionsSupport extends Object

A testing conversion of a value is exact if it yields a result without loss of information or throwing an exception. Otherwise, it is inexact. Some conversions are always exact regardless of the value. These conversions are said to be unconditionally exact.

For example, a conversion from int to byte for the value 10 is exact because the result, 10, is the same as the original value. In contrast, if the int variable i stores the value 1000 then a narrowing primitive conversion to byte will yield the result -24. Loss of information has occurred: both the magnitude and the sign of the result are different than those of the original value. As such, a conversion from int to byte for the value 1000 is inexact. Finally a widening primitive conversion from byte to int is unconditionally exact because it will always succeed with no loss of information about the magnitude of the numeric value.

The methods in this class provide the run-time support for the exactness checks of testing conversions from a primitive type to primitive type. These methods may be used, for example, by Java compiler implementations to implement checks for instanceof and pattern matching runtime implementations. Unconditionally exact testing conversions do not require a corresponding action at run time and, for this reason, methods corresponding to these exactness checks are omitted here.

The run time conversion checks examine whether loss of information would occur if a testing conversion would be to be applied. In those cases where a floating-point primitive type is involved, and the value of the testing conversion is either signed zero, signed infinity or NaN, these methods comply with the following:

Converting a floating-point negative zero to an integer type is considered inexact.
Converting a floating-point NaN or infinity to an integer type is considered inexact.
Converting a floating-point NaN or infinity or signed zero to another floating-point type is considered exact.

Implementation Note:: Some exactness checks describe a test which can be redirected safely through one of the existing methods. Those are omitted too (i.e., byte to char can be redirected to isIntToCharExact(int), short to byte can be redirected to isIntToByteExact(int) and similarly for short to char, char to byte and char to short to the corresponding methods that take an int).
See Java Language Specification:: 5.7.1 Exact Testing Conversions
5.7.2 Unconditionally Exact Testing Conversions
15.20.2 The instanceof Operator
Since:: 23

Method Summary

Modifier and Type	Method	Description
`static boolean`	`isDoubleToByteExact(double n)`	Exactness method from double to byte
`static boolean`	`isDoubleToCharExact(double n)`	Exactness method from double to char
`static boolean`	`isDoubleToFloatExact(double n)`	Exactness method from double to float
`static boolean`	`isDoubleToIntExact(double n)`	Exactness method from double to int
`static boolean`	`isDoubleToLongExact(double n)`	Exactness method from double to long
`static boolean`	`isDoubleToShortExact(double n)`	Exactness method from double to short
`static boolean`	`isFloatToByteExact(float n)`	Exactness method from float to byte
`static boolean`	`isFloatToCharExact(float n)`	Exactness method from float to char
`static boolean`	`isFloatToIntExact(float n)`	Exactness method from float to int
`static boolean`	`isFloatToLongExact(float n)`	Exactness method from float to long
`static boolean`	`isFloatToShortExact(float n)`	Exactness method from float to short
`static boolean`	`isIntToByteExact(int n)`	Exactness method from int to byte
`static boolean`	`isIntToCharExact(int n)`	Exactness method from int to char
`static boolean`	`isIntToFloatExact(int n)`	Exactness method from int to float
`static boolean`	`isIntToShortExact(int n)`	Exactness method from int to short
`static boolean`	`isLongToByteExact(long n)`	Exactness method from long to byte
`static boolean`	`isLongToCharExact(long n)`	Exactness method from long to char
`static boolean`	`isLongToDoubleExact(long n)`	Exactness method from long to double
`static boolean`	`isLongToFloatExact(long n)`	Exactness method from long to float
`static boolean`	`isLongToIntExact(long n)`	Exactness method from long to int
`static boolean`	`isLongToShortExact(long n)`	Exactness method from long to short

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

isIntToByteExact

public static boolean isIntToByteExact(int n)

Exactness method from int to byte

Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isIntToShortExact

public static boolean isIntToShortExact(int n)

Exactness method from int to short

Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isIntToCharExact

public static boolean isIntToCharExact(int n)

Exactness method from int to char

Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isIntToFloatExact

public static boolean isIntToFloatExact(int n)

Exactness method from int to float

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isLongToByteExact

public static boolean isLongToByteExact(long n)

Exactness method from long to byte

Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isLongToShortExact

public static boolean isLongToShortExact(long n)

Exactness method from long to short

Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isLongToCharExact

public static boolean isLongToCharExact(long n)

Exactness method from long to char

Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isLongToIntExact

public static boolean isLongToIntExact(long n)

Exactness method from long to int

Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isLongToFloatExact

public static boolean isLongToFloatExact(long n)

Exactness method from long to float

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isLongToDoubleExact

public static boolean isLongToDoubleExact(long n)

Exactness method from long to double

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isFloatToByteExact

public static boolean isFloatToByteExact(float n)

Exactness method from float to byte

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isFloatToShortExact

public static boolean isFloatToShortExact(float n)

Exactness method from float to short

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isFloatToCharExact

public static boolean isFloatToCharExact(float n)

Exactness method from float to char

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isFloatToIntExact

public static boolean isFloatToIntExact(float n)

Exactness method from float to int

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isFloatToLongExact

public static boolean isFloatToLongExact(float n)

Exactness method from float to long

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isDoubleToByteExact

public static boolean isDoubleToByteExact(double n)

Exactness method from double to byte

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isDoubleToShortExact

public static boolean isDoubleToShortExact(double n)

Exactness method from double to short

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isDoubleToCharExact

public static boolean isDoubleToCharExact(double n)

Exactness method from double to char

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isDoubleToIntExact

public static boolean isDoubleToIntExact(double n)

Exactness method from double to int

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isDoubleToLongExact

public static boolean isDoubleToLongExact(double n)

Exactness method from double to long

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

isDoubleToFloatExact

public static boolean isDoubleToFloatExact(double n)

Exactness method from double to float

Implementation Requirements:: relies on the notion of representation equivalence defined in the specification of the Double class.
Parameters:: n - value
Returns:: true if and only if the passed value can be converted exactly to the target type

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