public class SetUtils
extends java.lang.Object
Set
and SortedSet
instances.Modifier and Type | Field and Description |
---|---|
static java.util.Set |
EMPTY_SET
An empty unmodifiable set.
|
static java.util.SortedSet |
EMPTY_SORTED_SET
An empty unmodifiable sorted set.
|
Constructor and Description |
---|
SetUtils()
SetUtils should not normally be instantiated. |
Modifier and Type | Method and Description |
---|---|
static int |
hashCodeForSet(java.util.Collection set)
Generates a hash code using the algorithm specified in
Set.hashCode() . |
static boolean |
isEqualSet(java.util.Collection set1,
java.util.Collection set2)
Tests two sets for equality as per the
equals() contract
in Set.equals(java.lang.Object) . |
static java.util.Set |
orderedSet(java.util.Set set)
Returns a set that maintains the order of elements that are added
backed by the given set.
|
static java.util.Set |
predicatedSet(java.util.Set set,
Predicate predicate)
Returns a predicated (validating) set backed by the given set.
|
static java.util.SortedSet |
predicatedSortedSet(java.util.SortedSet set,
Predicate predicate)
Returns a predicated (validating) sorted set backed by the given sorted set.
|
static java.util.Set |
synchronizedSet(java.util.Set set)
Returns a synchronized set backed by the given set.
|
static java.util.SortedSet |
synchronizedSortedSet(java.util.SortedSet set)
Returns a synchronized sorted set backed by the given sorted set.
|
static java.util.Set |
transformedSet(java.util.Set set,
Transformer transformer)
Returns a transformed set backed by the given set.
|
static java.util.SortedSet |
transformedSortedSet(java.util.SortedSet set,
Transformer transformer)
Returns a transformed sorted set backed by the given set.
|
static java.util.Set |
typedSet(java.util.Set set,
java.lang.Class type)
Returns a typed set backed by the given set.
|
static java.util.SortedSet |
typedSortedSet(java.util.SortedSet set,
java.lang.Class type)
Returns a typed sorted set backed by the given set.
|
static java.util.Set |
unmodifiableSet(java.util.Set set)
Returns an unmodifiable set backed by the given set.
|
static java.util.SortedSet |
unmodifiableSortedSet(java.util.SortedSet set)
Returns an unmodifiable sorted set backed by the given sorted set.
|
public static final java.util.Set EMPTY_SET
Collections
implementation
and is provided for completeness.public static final java.util.SortedSet EMPTY_SORTED_SET
public static boolean isEqualSet(java.util.Collection set1, java.util.Collection set2)
equals()
contract
in Set.equals(java.lang.Object)
.
This method is useful for implementing Set
when you cannot
extend AbstractSet. The method takes Collection instances to enable other
collection types to use the Set implementation algorithm.
The relevant text (slightly paraphrased as this is a static method) is:
Two sets are considered equal if they have the same size, and every member of the first set is contained in the second. This ensures that the equals method works properly across different implementations of the Set interface.
This implementation first checks if the two sets are the same object: if so it returns true. Then, it checks if the two sets are identical in size; if not, it returns false. If so, it returns a.containsAll((Collection) b).
set1
- the first set, may be nullset2
- the second set, may be nullSet
public static int hashCodeForSet(java.util.Collection set)
Set.hashCode()
.
This method is useful for implementing Set
when you cannot
extend AbstractSet. The method takes Collection instances to enable other
collection types to use the Set implementation algorithm.
set
- the set to calculate the hash code for, may be nullSet.hashCode()
public static java.util.Set synchronizedSet(java.util.Set set)
You must manually synchronize on the returned buffer's iterator to avoid non-deterministic behavior:
Set s = SetUtils.synchronizedSet(mySet); synchronized (s) { Iterator i = s.iterator(); while (i.hasNext()) { process (i.next()); } }This method uses the implementation in the decorators subpackage.
set
- the set to synchronize, must not be nulljava.lang.IllegalArgumentException
- if the set is nullpublic static java.util.Set unmodifiableSet(java.util.Set set)
This method uses the implementation in the decorators subpackage.
set
- the set to make unmodifiable, must not be nulljava.lang.IllegalArgumentException
- if the set is nullpublic static java.util.Set predicatedSet(java.util.Set set, Predicate predicate)
Only objects that pass the test in the given predicate can be added to the set. Trying to add an invalid object results in an IllegalArgumentException. It is important not to use the original set after invoking this method, as it is a backdoor for adding invalid objects.
set
- the set to predicate, must not be nullpredicate
- the predicate for the set, must not be nulljava.lang.IllegalArgumentException
- if the Set or Predicate is nullpublic static java.util.Set typedSet(java.util.Set set, java.lang.Class type)
Only objects of the specified type can be added to the set.
set
- the set to limit to a specific type, must not be nulltype
- the type of objects which may be added to the setpublic static java.util.Set transformedSet(java.util.Set set, Transformer transformer)
Each object is passed through the transformer as it is added to the Set. It is important not to use the original set after invoking this method, as it is a backdoor for adding untransformed objects.
set
- the set to transform, must not be nulltransformer
- the transformer for the set, must not be nulljava.lang.IllegalArgumentException
- if the Set or Transformer is nullpublic static java.util.Set orderedSet(java.util.Set set)
If an element is added twice, the order is determined by the first add. The order is observed through the iterator or toArray.
set
- the set to order, must not be nulljava.lang.IllegalArgumentException
- if the Set is nullpublic static java.util.SortedSet synchronizedSortedSet(java.util.SortedSet set)
You must manually synchronize on the returned buffer's iterator to avoid non-deterministic behavior:
Set s = SetUtils.synchronizedSet(mySet); synchronized (s) { Iterator i = s.iterator(); while (i.hasNext()) { process (i.next()); } }This method uses the implementation in the decorators subpackage.
set
- the sorted set to synchronize, must not be nulljava.lang.IllegalArgumentException
- if the set is nullpublic static java.util.SortedSet unmodifiableSortedSet(java.util.SortedSet set)
This method uses the implementation in the decorators subpackage.
set
- the sorted set to make unmodifiable, must not be nulljava.lang.IllegalArgumentException
- if the set is nullpublic static java.util.SortedSet predicatedSortedSet(java.util.SortedSet set, Predicate predicate)
Only objects that pass the test in the given predicate can be added to the set. Trying to add an invalid object results in an IllegalArgumentException. It is important not to use the original set after invoking this method, as it is a backdoor for adding invalid objects.
set
- the sorted set to predicate, must not be nullpredicate
- the predicate for the sorted set, must not be nulljava.lang.IllegalArgumentException
- if the Set or Predicate is nullpublic static java.util.SortedSet typedSortedSet(java.util.SortedSet set, java.lang.Class type)
Only objects of the specified type can be added to the set.
set
- the set to limit to a specific type, must not be nulltype
- the type of objects which may be added to the setpublic static java.util.SortedSet transformedSortedSet(java.util.SortedSet set, Transformer transformer)
Each object is passed through the transformer as it is added to the Set. It is important not to use the original set after invoking this method, as it is a backdoor for adding untransformed objects.
set
- the set to transform, must not be nulltransformer
- the transformer for the set, must not be nulljava.lang.IllegalArgumentException
- if the Set or Transformer is null"Copyright © 2010 - 2020 Adobe Systems Incorporated. All Rights Reserved"