de.gsi.dataset.spi.utils

Class HashMapHelper

java.lang.Object

de.gsi.dataset.spi.utils.HashMapHelper

public final class HashMapHelper
extends Object

Common HashMap methods taken from FastUtil implementation

Method Summary

Modifier and Type	Method and Description
static int	arraySize(int expected, float f) Returns the least power of two smaller than or equal to 230 and larger than or equal to Math.ceil( expected / f ).
static long	nextPowerOfTwo(long length) Return the least power of two greater than or equal to the specified value.
static int	phiMix(int x)

Methods inherited from class java.lang.Object

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

Method Detail

arraySize

public static int arraySize(int expected,
                            float f)

Returns the least power of two smaller than or equal to 2³⁰ and larger than or equal to Math.ceil( expected / f ).

Parameters:

expected - the expected number of elements in a hash table.

f - the load factor.

Returns:

the minimum possible size for a backing array.

Throws:

IllegalArgumentException - if the necessary size is larger than 2³⁰.

nextPowerOfTwo

public static long nextPowerOfTwo(long length)

Return the least power of two greater than or equal to the specified value.

Note that this function will return 1 when the argument is 0.

Parameters:

length - a long integer smaller than or equal to 2⁶².

Returns:

the least power of two greater than or equal to the specified value.

phiMix

public static int phiMix(int x)