de.lmu.ifi.dbs.elki.utilities

Class Util

java.lang.Object

de.lmu.ifi.dbs.elki.utilities.Util

public final class Util
extends Object

This class collects various static helper methods. For helper methods related to special application fields see other utilities classes.

See Also:

de.lmu.ifi.dbs.elki.utilities

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	Util.ForwardComparator Regular comparator.

Field Summary

Fields

Modifier and Type	Field and Description
private static Comparator<?>	FORWARD Static instance.
private static long	HASHPRIME Prime number used in hash code computation.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	Util() Fake constructor: do not instantiate.

Method Summary

Methods

Modifier and Type	Method and Description
static <T> Comparator<T>	forwardOrder() Compare two objects, forward.
static int	mixHashCodes(int... hash) Mix multiple hashcodes into one.
static int	mixHashCodes(int hash) Deprecated.
static int	mixHashCodes(int hash1, int hash2) Mix multiple hashcodes into one.
static int	mixHashCodes(int hash1, int hash2, int hash3) Mix multiple hashcodes into one.
static BitSet	randomBitSet(int cardinality, int capacity, Random random) Creates a new BitSet of fixed cardinality with randomly set bits.

Methods inherited from class java.lang.Object

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

Field Detail

HASHPRIME

private static final long HASHPRIME

Prime number used in hash code computation.

See Also:

Constant Field Values

FORWARD

private static final Comparator<?> FORWARD

Static instance.

Constructor Detail

Util

private Util()

Fake constructor: do not instantiate.

Method Detail

randomBitSet

public static BitSet randomBitSet(int cardinality,
                  int capacity,
                  Random random)

Creates a new BitSet of fixed cardinality with randomly set bits.

Parameters:

cardinality - the cardinality of the BitSet to create

capacity - the capacity of the BitSet to create - the randomly generated indices of the bits set to true will be uniformly distributed between 0 (inclusive) and capacity (exclusive)

random - a Random Object to create the sequence of indices set to true - the same number occurring twice or more is ignored but the already selected bit remains true

Returns:

a new BitSet with randomly set bits

mixHashCodes

@Deprecated
public static int mixHashCodes(int hash)

Deprecated.

Mix multiple hashcodes into one.

Parameters:

hash - Single Hashcodes to "mix"

Returns:

Original hash code

mixHashCodes

public static int mixHashCodes(int hash1,
               int hash2)

Mix multiple hashcodes into one.

Parameters:

hash1 - First hashcode to mix

hash2 - Second hashcode to mix

Returns:

Mixed hash code

mixHashCodes

public static int mixHashCodes(int hash1,
               int hash2,
               int hash3)

Mix multiple hashcodes into one.

Parameters:

hash1 - First hashcode to mix

hash2 - Second hashcode to mix

hash3 - Third hashcode to mix

Returns:

Mixed hash code

mixHashCodes

public static int mixHashCodes(int... hash)

Mix multiple hashcodes into one.

Parameters:

hash - Hashcodes to mix

Returns:

Mixed hash code

forwardOrder

public static <T> Comparator<T> forwardOrder()

Compare two objects, forward. See Collections.reverseOrder() for a reverse comparator.

Type Parameters:

T - Object type

Returns:

Forward comparator