org.teiid.core.util

Class HashCodeUtil

java.lang.Object

org.teiid.core.util.HashCodeUtil

public final class HashCodeUtil
extends Object

This class provides utility functions for generating good hash codes. Hash codes generated with these methods should have a reasonably good distribution when placed in a hash structure such as Hashtable, HashSet, or HashMap.

General usage is something like:

 public int hashCode() {
     int hc = 0;        // or = super.hashCode();
     hc = HashCodeUtil.hashCode(hc, intField);
     hc = HashCodeUtil.hashCode(hc, objectField);
     // etc, etc
     return hc;
 }
 

Constructor Summary

Constructors

Constructor and Description
HashCodeUtil()

Method Summary

Modifier and Type	Method and Description
static int	expHashCode(CharSequence x)
static int	expHashCode(CharSequence x, boolean caseSensitive)
static int	expHashCode(int previous, Collection<?> x) Compute a hash code on a large collection by walking the list and combining the hash code at every exponential index: 1, 2, 4, 8, ...
static int	expHashCode(int previous, Object[] x) Compute a hash code on a large array by walking the list and combining the hash code at every exponential index: 1, 2, 4, 8, ...
static int	hashCode(int previous, boolean x)
static int	hashCode(int previous, double x)
static int	hashCode(int previous, float x)
static int	hashCode(int previous, int x)
static int	hashCode(int previous, long x)
static int	hashCode(int previous, Object... x)

Methods inherited from class java.lang.Object

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

Constructor Detail

HashCodeUtil

public HashCodeUtil()

Method Detail

hashCode

public static final int hashCode(int previous,
                                 boolean x)

hashCode

public static final int hashCode(int previous,
                                 int x)

hashCode

public static final int hashCode(int previous,
                                 long x)

hashCode

public static final int hashCode(int previous,
                                 float x)

hashCode

public static final int hashCode(int previous,
                                 double x)

hashCode

public static final int hashCode(int previous,
                                 Object... x)

expHashCode

public static final int expHashCode(int previous,
                                    Object[] x)

Compute a hash code on a large array by walking the list and combining the hash code at every exponential index: 1, 2, 4, 8, ... This has been shown to give a good hash for good time complexity.

expHashCode

public static final int expHashCode(int previous,
                                    Collection<?> x)

Compute a hash code on a large collection by walking the list and combining the hash code at every exponential index: 1, 2, 4, 8, ... This has been shown to give a good hash for good time complexity.

expHashCode

public static final int expHashCode(CharSequence x)

expHashCode

public static final int expHashCode(CharSequence x,
                                    boolean caseSensitive)