OpenJDK 27 · java.lang.runtime.ExactConversionsSupport

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.

Constructor Summary

Access	Constructor and Description
private	ExactConversionsSupport()

Method Summary

Modifier and Type	Method and Description
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isDoubleToByteExact(double value n) Exactness method from double to byte
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isDoubleToCharExact(double value n) Exactness method from double to char
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isDoubleToFloatExact(double value n) Exactness method from double to float
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isDoubleToIntExact(double value n) Exactness method from double to int
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isDoubleToLongExact(double value n) Exactness method from double to long
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isDoubleToShortExact(double value n) Exactness method from double to short
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isFloatToByteExact(float value n) Exactness method from float to byte
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isFloatToCharExact(float value n) Exactness method from float to char
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isFloatToIntExact(float value n) Exactness method from float to int
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isFloatToLongExact(float value n) Exactness method from float to long
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isFloatToShortExact(float value n) Exactness method from float to short
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isIntToByteExact(int value n) Exactness method from int to byte
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isIntToCharExact(int value n) Exactness method from int to char
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isIntToFloatExact(int value n) Exactness method from int to float
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isIntToShortExact(int value n) Exactness method from int to short
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isLongToByteExact(long value n) Exactness method from long to byte
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isLongToCharExact(long value n) Exactness method from long to char
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isLongToDoubleExact(long value n) Exactness method from long to double
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isLongToFloatExact(long value n) Exactness method from long to float
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isLongToIntExact(long value n) Exactness method from long to int
public static boolean	Returns: true if and only if the passed value can be converted exactly to the target type isLongToShortExact(long value n) Exactness method from long to short
private static boolean	isNegativeZero(float n)
private static boolean	isNegativeZero(double n)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Constructor Detail

ExactConversionsSupport	back to summary
private ExactConversionsSupport()

Method Detail

isDoubleToByteExact	back to summary
public static boolean isDoubleToByteExact(double n) Exactness method from double to byte Implementation Specification relies on the notion of representation equivalence defined in the specification of the Double class. Parameters n:double value Returns:boolean true if and only if the passed value can be converted exactly to the target type

isDoubleToByteExact

public final Class ExactConversionsSupport

Constructor Summary

Method Summary

Constructor Detail

Method Detail