com.sun.j3d.internal

Class HashCodeUtil

java.lang.Object

com.sun.j3d.internal.HashCodeUtil

public class HashCodeUtil
extends Object

Utility class used when computing the hash code for objects containing float or double values. This fixes Issue 36.

Method Summary

Methods

Modifier and Type	Method and Description
static long	doubleToLongBits(double d) Returns the representation of the specified floating-point value according to the IEEE 754 floating-point "double format" bit layout, after first mapping -0.0 to 0.0.
static int	floatToIntBits(float f) Returns the representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout, after first mapping -0.0 to 0.0.

Methods inherited from class java.lang.Object

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

Method Detail

floatToIntBits

public static int floatToIntBits(float f)

Returns the representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout, after first mapping -0.0 to 0.0. This method is identical to Float.floatToIntBits(float) except that an integer value of 0 is returned for a floating-point value of -0.0f. This is done for the purpose of computing a hash code that satisfies the contract of hashCode() and equals(). The equals() method in some Java 3D classes does a pair-wise "==" test on each floating-point field in the class. Since 0.0f == -0.0f returns true, we must also return the same hash code for two objects, one of which has a field with a value of -0.0f and the other of which has a cooresponding field with a value of 0.0f.

Parameters:

f - an input floating-point number

Returns:

the integer bits representing that floating-point number, after first mapping -0.0f to 0.0f

doubleToLongBits

public static long doubleToLongBits(double d)

Returns the representation of the specified floating-point value according to the IEEE 754 floating-point "double format" bit layout, after first mapping -0.0 to 0.0. This method is identical to Double.doubleToLongBits(double) except that an integer value of 0L is returned for a floating-point value of -0.0. This is done for the purpose of computing a hash code that satisfies the contract of hashCode() and equals(). The equals() method in some Java 3D classes does a pair-wise "==" test on each floating-point field in the class. Since 0.0 == -0.0 returns true, we must also return the same hash code for two objects, one of which has a field with a value of -0.0 and the other of which has a cooresponding field with a value of 0.0.

Parameters:

d - an input double precision floating-point number

Returns:

the integer bits representing that floating-point number, after first mapping -0.0f to 0.0f