LinkedHashSet Class
Definition
Important
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Hash table and linked list implementation of the Set interface,
with predictable iteration order.
[Android.Runtime.Register("java/util/LinkedHashSet", DoNotGenerateAcw=true)]
[Java.Interop.JavaTypeParameters(new System.String[] { "E" })]
public class LinkedHashSet : Java.Util.HashSet, IDisposable, Java.Interop.IJavaPeerable[<Android.Runtime.Register("java/util/LinkedHashSet", DoNotGenerateAcw=true)>]
[<Java.Interop.JavaTypeParameters(new System.String[] { "E" })>]
type LinkedHashSet = class
inherit HashSet
interface ISerializable
interface IJavaObject
interface IDisposable
interface IJavaPeerable
interface ICloneable
interface ISet
interface ICollection
interface IIterable- Inheritance
- Attributes
- Implements
Remarks
Hash table and linked list implementation of the Set interface, with predictable iteration order. This implementation differs from HashSet in that it maintains a doubly-linked list running through all of its entries. This linked list defines the iteration ordering, which is the order in which elements were inserted into the set (insertion-order). Note that insertion order is not affected if an element is re-inserted into the set. (An element e is reinserted into a set s if s.add(e) is invoked when s.contains(e) would return true immediately prior to the invocation.)
This implementation spares its clients from the unspecified, generally chaotic ordering provided by HashSet, without incurring the increased cost associated with TreeSet. It can be used to produce a copy of a set that has the same order as the original, regardless of the original set's implementation:
{@code
void foo(Set<String> s) {
Set<String> copy = new LinkedHashSet<>(s);
...
}
}
This technique is particularly useful if a module takes a set on input, copies it, and later returns results whose order is determined by that of the copy. (Clients generally appreciate having things returned in the same order they were presented.)
This class provides all of the optional Set operations, and permits null elements. Like HashSet, it provides constant-time performance for the basic operations (add, contains and remove), assuming the hash function disperses elements properly among the buckets. Performance is likely to be just slightly below that of HashSet, due to the added expense of maintaining the linked list, with one exception: Iteration over a LinkedHashSet requires time proportional to the size of the set, regardless of its capacity. Iteration over a HashSet is likely to be more expensive, requiring time proportional to its capacity.
A linked hash set has two parameters that affect its performance: initial capacity and load factor. They are defined precisely as for HashSet. Note, however, that the penalty for choosing an excessively high value for initial capacity is less severe for this class than for HashSet, as iteration times for this class are unaffected by capacity.
<strong>Note that this implementation is not synchronized.</strong> If multiple threads access a linked hash set concurrently, and at least one of the threads modifies the set, it <em>must</em> be synchronized externally. This is typically accomplished by synchronizing on some object that naturally encapsulates the set.
If no such object exists, the set should be "wrapped" using the Collections#synchronizedSet Collections.synchronizedSet method. This is best done at creation time, to prevent accidental unsynchronized access to the set:
Set s = Collections.synchronizedSet(new LinkedHashSet(...));
The iterators returned by this class's iterator method are <em>fail-fast</em>: if the set is modified at any time after the iterator is created, in any way except through the iterator's own remove method, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.
Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.
This class is a member of the Java Collections Framework.
Added in 1.4.
Java documentation for java.util.LinkedHashSet.
Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.
Constructors
| LinkedHashSet() |
Constructs a new, empty linked hash set with the default initial capacity (16) and load factor (0. |
| LinkedHashSet(ICollection) |
Constructs a new linked hash set with the same elements as the specified collection. |
| LinkedHashSet(Int32, Single) |
Constructs a new, empty linked hash set with the specified initial capacity and load factor. |
| LinkedHashSet(Int32) |
Constructs a new, empty linked hash set with the specified initial capacity and the default load factor (0. |
| LinkedHashSet(IntPtr, JniHandleOwnership) |
A constructor used when creating managed representations of JNI objects; called by the runtime. |
Properties
| Class |
Returns the runtime class of this |
| Handle |
The handle to the underlying Android instance. (Inherited from Object) |
| IsEmpty |
To be added (Inherited from AbstractCollection) |
| JniIdentityHashCode | (Inherited from Object) |
| JniPeerMembers | |
| PeerReference | (Inherited from Object) |
| ThresholdClass |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. |
| ThresholdType |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. |
Methods
| Add(Object) |
To be added (Inherited from AbstractCollection) |
| AddAll(ICollection) |
To be added (Inherited from AbstractCollection) |
| Clear() |
To be added (Inherited from AbstractCollection) |
| Clone() |
Returns a shallow copy of this |
| Contains(Object) |
To be added (Inherited from AbstractCollection) |
| ContainsAll(ICollection) |
To be added (Inherited from AbstractCollection) |
| Dispose() | (Inherited from Object) |
| Dispose(Boolean) | (Inherited from Object) |
| Equals(Object) |
Indicates whether some other object is "equal to" this one. (Inherited from Object) |
| GetHashCode() |
Returns a hash code value for the object. (Inherited from Object) |
| Iterator() |
Returns an iterator over the elements in this set. (Inherited from HashSet) |
| JavaFinalize() |
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. (Inherited from Object) |
| Notify() |
Wakes up a single thread that is waiting on this object's monitor. (Inherited from Object) |
| NotifyAll() |
Wakes up all threads that are waiting on this object's monitor. (Inherited from Object) |
| Remove(Object) |
To be added (Inherited from AbstractCollection) |
| RemoveAll(ICollection) |
To be added (Inherited from AbstractCollection) |
| RetainAll(ICollection) |
To be added (Inherited from AbstractCollection) |
| SetHandle(IntPtr, JniHandleOwnership) |
Sets the Handle property. (Inherited from Object) |
| Size() |
Returns the number of elements in this set (its cardinality). (Inherited from HashSet) |
| Spliterator() |
Creates a <em>late-binding</em>
and <em>fail-fast</em> |
| ToArray() |
To be added (Inherited from AbstractCollection) |
| ToArray(Object[]) |
To be added (Inherited from AbstractCollection) |
| ToArray<T>() | (Inherited from Object) |
| ToString() |
Returns a string representation of the object. (Inherited from Object) |
| UnregisterFromRuntime() | (Inherited from Object) |
| Wait() |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>. (Inherited from Object) |
| Wait(Int64, Int32) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
| Wait(Int64) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
Explicit Interface Implementations
| IJavaPeerable.Disposed() | (Inherited from Object) |
| IJavaPeerable.DisposeUnlessReferenced() | (Inherited from Object) |
| IJavaPeerable.Finalized() | (Inherited from Object) |
| IJavaPeerable.JniManagedPeerState | (Inherited from Object) |
| IJavaPeerable.SetJniIdentityHashCode(Int32) | (Inherited from Object) |
| IJavaPeerable.SetJniManagedPeerState(JniManagedPeerStates) | (Inherited from Object) |
| IJavaPeerable.SetPeerReference(JniObjectReference) | (Inherited from Object) |
Extension Methods
| JavaCast<TResult>(IJavaObject) |
Performs an Android runtime-checked type conversion. |
| JavaCast<TResult>(IJavaObject) | |
| GetJniTypeName(IJavaPeerable) | |
| ToEnumerable(IIterable) | |
| ToEnumerable<T>(IIterable) | |