io.github.andyalvarez.primitive.LinkedHashLongSet Maven / Gradle / Ivy
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package io.github.andyalvarez.primitive;
import java.util.*;
/**
* Hash table and linked list implementation of the {@code Set} interface,
* with predictable iteration order. This implementation differs from
* {@code 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 {@code e}
* is reinserted into a set {@code s} if {@code s.add(e)} is invoked when
* {@code s.contains(e)} would return {@code true} immediately prior to
* the invocation.)
*
*
This implementation spares its clients from the unspecified, generally
* chaotic ordering provided by {@link HashSet}, without incurring the
* increased cost associated with {@link 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:
*
* void foo(Set s) {
* Set 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 {@code Set} operations, and
* permits null elements. Like {@code HashSet}, it provides constant-time
* performance for the basic operations ({@code add}, {@code contains} and
* {@code remove}), assuming the hash function disperses elements
* properly among the buckets. Performance is likely to be just slightly
* below that of {@code HashSet}, due to the added expense of maintaining the
* linked list, with one exception: Iteration over a {@code LinkedHashSet}
* requires time proportional to the size of the set, regardless of
* its capacity. Iteration over a {@code 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 {@code HashSet}. Note, however, that the penalty for choosing an
* excessively high value for initial capacity is less severe for this class
* than for {@code HashSet}, as iteration times for this class are unaffected
* by capacity.
*
*
Note that this implementation is not synchronized.
* If multiple threads access a linked hash set concurrently, and at least
* one of the threads modifies the set, it must be synchronized
* externally. This is typically accomplished by synchronizing on some
* object that naturally encapsulates the set.
*
*
The iterators returned by this class's {@code iterator} method are
* fail-fast: if the set is modified at any time after the iterator
* is created, in any way except through the iterator's own {@code remove}
* method, the iterator will throw a {@link 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 {@code 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.
*
* @author Josh Bloch
* @see Object#hashCode()
* @see Collection
* @see Set
* @see HashSet
* @see TreeSet
* @see Hashtable
* @since 1.4
*/
public class LinkedHashLongSet
extends HashLongSet
implements LongSet, Cloneable, java.io.Serializable {
private static final long serialVersionUID = -2851667679971038690L;
/**
* Constructs a new, empty linked hash set with the specified initial
* capacity and load factor.
*
* @param initialCapacity the initial capacity of the linked hash set
* @param loadFactor the load factor of the linked hash set
* @throws IllegalArgumentException if the initial capacity is less
* than zero, or if the load factor is nonpositive
*/
public LinkedHashLongSet(int initialCapacity, float loadFactor) {
super(initialCapacity, loadFactor, true);
}
/**
* Constructs a new, empty linked hash set with the specified initial
* capacity and the default load factor (0.75).
*
* @param initialCapacity the initial capacity of the LinkedHashSet
* @throws IllegalArgumentException if the initial capacity is less
* than zero
*/
public LinkedHashLongSet(int initialCapacity) {
super(initialCapacity, .75f, true);
}
/**
* Constructs a new, empty linked hash set with the default initial
* capacity (16) and load factor (0.75).
*/
public LinkedHashLongSet() {
super(16, .75f, true);
}
/**
* Constructs a new linked hash set with the same elements as the
* specified collection. The linked hash set is created with an initial
* capacity sufficient to hold the elements in the specified collection
* and the default load factor (0.75).
*
* @param c the collection whose elements are to be placed into
* this set
* @throws NullPointerException if the specified collection is null
*/
public LinkedHashLongSet(LongCollection c) {
super(Math.max(2*c.size(), 11), .75f, true);
addAll(c);
}
/**
* Creates a late-binding
* and fail-fast {@code Spliterator} over the elements in this set.
*
*
The {@code Spliterator} reports {@link Spliterator#SIZED},
* {@link Spliterator#DISTINCT}, and {@code ORDERED}. Implementations
* should document the reporting of additional characteristic values.
*
*
* The implementation creates a
* late-binding spliterator
* from the set's {@code Iterator}. The spliterator inherits the
* fail-fast properties of the set's iterator.
* The created {@code Spliterator} additionally reports
* {@link Spliterator#SUBSIZED}.
*
* @return a {@code Spliterator} over the elements in this set
* @since 1.8
*/
@Override
public Spliterator.OfLong spliterator() {
return Spliterators.spliterator(iterator(), size(), Spliterator.DISTINCT | Spliterator.ORDERED);
}
}