org.stekikun.dolmen.common

Class Sets

java.lang.Object

org.stekikun.dolmen.common.Sets

public abstract class Sets
extends Object

This class contains various utility methods about Sets. The various operations like union(Set, Set) and so on assume an immutable use of the sets used as parameters, since they are optimized to return one of the input sets instead of new sets when possible. I wished I had Guava available!

Author:

Stéphane Lescuyer

Method Summary

Modifier and Type	Method and Description
static <T> Set<T>	add(T elt, Set<T> s)
static <T> Set<T>	create()
static <T> Set<T>	diff(Set<T> s1, Set<T> s2)
static <T> Set<T>	empty()
static <T> Set<T>	inter(Set<T> s1, Set<T> s2)
static <T> Set<T>	singleton(T elt)
static <T> Set<T>	symdiff(Set<T> s1, Set<T> s2)
static <T> Set<T>	union(Set<T> s1, Set<T> s2)

Methods inherited from class java.lang.Object

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

Method Detail

empty

public static <T> Set<T> empty()

Returns:

the empty unmodifiable set

singleton

public static <T> Set<T> singleton(T elt)

Parameters:

elt -

Returns:

the singleton set containing elt

add

public static <T> Set<T> add(T elt,
                             Set<T> s)

Parameters:

elt -

s -

Returns:

a set where x has been added to the elements of s

union

public static <T> Set<T> union(Set<T> s1,
                               Set<T> s2)

Parameters:

s1 -

s2 -

Returns:

the union of s1 and s2

inter

public static <T> Set<T> inter(Set<T> s1,
                               Set<T> s2)

Parameters:

s1 -

s2 -

Returns:

the intersection of s1 and s2

diff

public static <T> Set<T> diff(Set<T> s1,
                              Set<T> s2)

Parameters:

s1 -

s2 -

Returns:

the set of elements in s1 and not in s2

symdiff

public static <T> Set<T> symdiff(Set<T> s1,
                                 Set<T> s2)

Parameters:

s1 -

s2 -

Returns:

the symmetric difference between s1 and s2

create

public static <T> Set<T> create()

Returns:

a freshly allocated hash-set