FastCollection (Javolution Core (Java) 6.0.0 API)

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javolution.util

Class FastCollection<E>

java.lang.Object
- javolution.util.FastCollection<E>

All Implemented Interfaces:: Serializable, Iterable<E>, Collection<E>

Direct Known Subclasses:: FastSet, FastTable

@Realtime
@DefaultTextFormat(value=FastCollection.Format.class)
public abstract class FastCollection<E>
extends Object
implements Collection<E>, Serializable

A closure-based collection supporting numerous views which can be chained.

atomic() - Thread-safe view for which all reads are mutex-free and collection updates (including addAll, removeIf} are atomic.
shared() - Thread-safe view using allowing concurrent reads based on mutex ( readers-writer locks).

parallel() - A view allowing parallel processing including updates.
sequential() - View disallowing parallel processing.
unmodifiable() - View which does not allow any modification.
filtered(filter) - View exposing only the elements matching the specified filter.
mapped(function) - View exposing elements through the specified mapping function.
sorted(comparator) - View exposing elements sorted according to their natural order of using a specified comparator.
reversed() - View exposing elements in the reverse iterative order.
distinct() - View exposing each element only once.

Unmodifiable collections are not always immutable. An immutable. reference (or const reference) can only be obtained when the originator guarantees that the collection source will not be modified even by himself (the value of the immutable reference being an unmodifiable collection).

 Immutable<List<String>> winners 
 = new FastTable<String>().addAll("John Deuff", "Otto Graf", "Sim Kamil").toImmutable();
 // Immutability is guaranteed, no reference left on the collection source.

Atomic collections use Copy-On-Write optimizations in order to provide mutex-free read access. Only writes operations are mutually exclusive. Collections can be optimized to not require the full copy during write operations (e.g. immutable parts don't need to be copied). Still, when multiple updates are performed, it is beneficial to group them into one single update operation.

 FastTable<String> tokens = ...
 ...
 // Replace null with "" in tokens. If tokens is atomic the update is atomic.
 // If tokens is parallel, the update is also performed concurrently !
 tokens.update(new Consumer<List<String>>() { 
 public void accept(List<String> view) {
 for (int i=0, n = view.size(); i < n; i++)
 if (view.get(i) == null) view.set(i, "");
 }
 }
 });

The same code using closure (Java 8).

 tokens.update((List<String> view) -> {
 for (int i = 0, n = view.size(); i < n; i++) {
 if (view.get(i) == null) view.set(i, "");
 }
 });

Views are similar to Java 8 streams except that views are themselves collections (virtual collections) and actions on a view can impact the original collection. Collection views are nothing "new" since they already existed in the original java.util collection classes (e.g. List.subList(...), Map.keySet(), Map.values()). Javolution extends to this concept and allows views to be chained which addresses the concern of class proliferation.

 FastTable<String> names = new FastTable<String>().addAll("Oscar Thon", "Eva Poret", "Paul Auchon");
 boolean found = names.comparator(Equalities.LEXICAL_CASE_INSENSITIVE).contains("LUC SURIEUX"); 
 names.subTable(0, n).clear(); // Removes the n first names (see java.util.List.subList).
 names.distinct().add("Guy Liguili"); // Adds "Guy Liguili" only if not already present.
 names.filtered(isLong).clear(); // Removes all the persons with long names.
 names.filtered(isLong).parallel().clear(); // Same as above but performed concurrently !
 ...
 Predicate<CharSequence> isLong = new Predicate<CharSequence>() { 
 public boolean test(CharSequence csq) {
 return csq.length() > 16; 
 }
 });

Views can of course be used to perform "stream" oriented filter-map-reduce operations with the same benefits: Parallelism support, excellent memory characteristics (no caching and cost nothing to create), etc.

 String anyLongName = names.filtered(isLong).any(String.class); // Returns any long name.
 int nbrChars = names.mapped(toLength).reduce(Reducers.sum()); // Returns the total number of characters.
 int maxLength = names.mapped(toLength).parallel().max(); // Finds the longest name in parallel.
 ...
 Function<CharSequence, Integer> toLength = new Function<CharSequence, Integer>() {
 public Integer apply(CharSequence csq) {
 return csq.length(); 
 }
 });
 
 // JDK Class.getEnclosingMethod using Javolution's views and Java 8 (to be compared with the current 20 lines implementation !).
 Method matching = new FastTable<Method>().addAll(enclosingInfo.getEnclosingClass().getDeclaredMethods())
 .filtered(m -> Equalities.STANDARD.areEqual(m.getName(), enclosingInfo.getName())
 .filtered(m -> Equalities.ARRAY.areEqual(m.getParameterTypes(), parameterClasses))
 .filtered(m -> Equalities.STANDARD.areEqual(m.getReturnType(), returnType))
 .any(Method.class);
 if (matching == null) throw new InternalError("Enclosing method not found");
 return matching;

If a collection (or a map) is shared, derived views are also thread-safe. Similarly, if a collection is parallel, closure-based iterations on derived views are performed concurrently.

 FastMap<String, Runnable> tasks = ...
 ...
 tasks.values().parallel().forEach(new Consumer<Runnable>() { // Executes task concurrently. 
 public void accept(Runnable task) {
 task.run();
 }
 });

With Java 8, closures are greatly simplified using lambda expressions.

 tasks.values().parallel().forEach(task -> task.run()); // Same as above.
 names.sorted().reversed().forEach(str -> System.out.println(str)); // Prints names in reverse alphabetical order.

Version:: 6.0, July 21, 2013
Author:: Jean-Marie Dautelle
See Also:: Serialized Form

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class FastCollection.Format
Default text format for fast collections (parsing not supported).

Nested Classes
Modifier and Type	Class and Description
`static class`	`FastCollection.Format` Default text format for fast collections (parsing not supported).

Constructor Summary

Constructors
Modifier Constructor and Description

protected FastCollection ()
Default constructor.

Constructors
Modifier	Constructor and Description
`protected`	`FastCollection ()` Default constructor.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`add (E element)` Adds the specified element to this collection
`boolean`	`addAll (Collection<? extends E> that)` Adds all the specified elements to this collection.
`FastCollection<E>`	`addAll (E... elements)` Returns this collection with the specified element added.
`FastCollection<E>`	`addAll (FastCollection<? extends E> that)` Returns this collection with the specified collection's elements added in sequence.
`<T extends E> T`	`any (Class<T> type)` Returns any non-null element of the specified type (convenience method).
`FastCollection<E>`	`atomic ()` Returns an atomic view over this collection.
`void`	`clear ()` Removes all elements from this collection.
`Equality<? super E>`	`comparator ()` Returns the comparator uses by this collection for equality and/or ordering if this collection is sorted.
`boolean`	`contains (Object searched)` Indicates if this collection contains the specified element.
`boolean`	`containsAll (Collection<?> that)` Indicates if this collection contains all the specified elements.
`FastCollection<E>`	`distinct ()` Returns a view exposing only distinct elements (it does not iterate twice over the `same` elements).
`boolean`	`equals (Object obj)` Compares the specified object with this collection for equality.
`FastCollection<E>`	`filtered (Predicate<? super E> filter)` Returns a view exposing only the elements matching the specified filter.
`void`	`forEach (Consumer<? super E> consumer)` Iterates over all this collection elements applying the specified consumer (convenience method).
`int`	`hashCode ()` Returns the hash code of this collection.
`boolean`	`isEmpty ()` Indicates if this collection is empty.
`Iterator<E>`	`iterator ()` Returns an iterator over this collection elements.
`<R> FastCollection<R>`	`mapped (Function<? super E,? extends R> function)` Returns a view exposing elements through the specified mapping function.
`E`	`max ()` Returns the largest element of this collection using this collection `comparator` (convenience method).
`E`	`min ()` Returns the smallest element of this collection using this collection `comparator` (convenience method).
`FastCollection<E>`	`parallel ()` Returns a parallel collection.
`void`	`perform (Consumer<? extends Collection<E>> action)` Executes the specified read-only action on this collection.
`E`	`reduce (Reducer<E> reducer)` Performs a reduction of the elements of this collection using the specified reducer.
`boolean`	`remove (Object searched)` Removes the specified element from this collection.
`boolean`	`removeAll (Collection<?> that)` Removes all the specified element from this collection.
`boolean`	`removeIf (Predicate<? super E> filter)` Removes from this collection all the elements matching the specified functional predicate (convenience method).
`boolean`	`retainAll (Collection<?> that)` Removes all the elements except those in the specified collection.
`FastCollection<E>`	`reversed ()` Returns a view exposing elements in reverse iterative order.
`FastCollection<E>`	`sequential ()` Returns a sequential view of this collection.
`protected abstract CollectionService<E>`	`service ()` Returns the service implementation of this collection (for sub-classes).
`protected static <E> CollectionService<E>`	`serviceOf (FastCollection<E> collection)` Returns the service implementation of any fast collection (for sub-classes).
`FastCollection<E>`	`shared ()` Returns a thread-safe view over this collection.
`int`	`size ()` Returns the size of this collection.
`FastCollection<E>`	`sorted ()` Returns a view exposing elements sorted according to the collection `order`.
`FastCollection<E>`	`sorted (Comparator<? super E> cmp)` Returns a view exposing elements sorted according to the specified comparator.
`Object[]`	`toArray ()` Returns an array holding this collection elements.
`<T> T[]`	`toArray (T[] array)` Returns the specified array holding this collection elements if enough capacity.
`<T extends Collection<E>> Immutable<T>`	`toImmutable ()` Returns an immutable reference over this collection.
`String`	`toString ()` Returns the string representation of this collection using its default `format`.
`FastCollection<E>`	`unmodifiable ()` Returns an unmodifiable view over this collection.
`void`	`update (Consumer<? extends Collection<E>> action)` Executes the specified update action on this collection.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - FastCollection
```
protected FastCollection()
```
    Default constructor.
- Method Detail
  - atomic
```
@Parallelizable(mutexFree=true,
 comment="Except for write operations, all read operations are mutex-free.")
public FastCollection<E> atomic()
```
    Returns an atomic view over this collection. All operations that write or access multiple elements in the collection (such as addAll(), retainAll()) are atomic. Iterators on atomic collections are thread-safe (no ConcurrentModificationException possible).
  - shared
```
@Parallelizable(mutexFree=false,
 comment="Use multiple-readers/single-writer lock.")
public FastCollection<E> shared()
```
    Returns a thread-safe view over this collection. The shared view allows for concurrent read as long as there is no writer. The default implementation is based on readers-writers locks giving priority to writers. Iterators on shared collections are thread-safe (no ConcurrentModificationException possible).
  - parallel
```
public FastCollection<E> parallel()
```
    Returns a parallel collection. Parallel collections affect only closure-based operations, all others operations behaving the same. Parallel actions are performed concurrently using Javolution ConcurrentContext. The number of parallel views is derived from the context concurrency (number of parallel views = concurrency + 1). Parallel views do not require this collection to be thread-safe (internal synchronization).
    
    See Also:
    perform(Consumer), update(Consumer), forEach(Consumer), removeIf(Predicate), reduce(Reducer)
  - sequential
```
public FastCollection<E> sequential()
```
    Returns a sequential view of this collection. Using this view, all closure-based iterations are performed sequentially.
  - unmodifiable
```
public FastCollection<E> unmodifiable()
```
    Returns an unmodifiable view over this collection. Any attempt to modify the collection through this view will result into a UnsupportedOperationException being raised.
  - filtered
```
public FastCollection<E> filtered(Predicate<? super E> filter)
```
    Returns a view exposing only the elements matching the specified filter. Adding elements not matching the specified filter has no effect. If this collection is initially empty, using a filtered view to add new elements ensure that this collection has only elements satisfying the filter predicate.
  - mapped
```
public <R> FastCollection<R> mapped(Function<? super E,? extends R> function)
```
    Returns a view exposing elements through the specified mapping function. The returned view does not allow new elements to be added.
  - sorted
```
public FastCollection<E> sorted()
```
    Returns a view exposing elements sorted according to the collection order.
  - sorted
```
public FastCollection<E> sorted(Comparator<? super E> cmp)
```
    Returns a view exposing elements sorted according to the specified comparator.
  - reversed
```
public FastCollection<E> reversed()
```
    Returns a view exposing elements in reverse iterative order.
  - distinct
```
public FastCollection<E> distinct()
```
    Returns a view exposing only distinct elements (it does not iterate twice over the same elements). Adding elements already in the collection through this view has no effect. If this collection is initially empty, using a distinct view to add new elements ensures that this collection has no duplicate.
  - perform
```
@Realtime(limit=LINEAR)
public void perform(Consumer<? extends Collection<E>> action)
```
    Executes the specified read-only action on this collection. That logic may be performed concurrently on sub-collections if this collection is parallel.
    
    Parameters:
    action - the read-only action.
    
    Throws:
    
    UnsupportedOperationException - if the action tries to update this collection and this collection is thread-safe.
    
    ClassCastException - if the action type is not compatible with this collection (e.g. action on set and this is a list).
    See Also:
    update(Consumer)
  - update
```
@Realtime(limit=LINEAR)
public void update(Consumer<? extends Collection<E>> action)
```
    Executes the specified update action on this collection. That logic may be performed concurrently on sub-collections if this collection is parallel. For atomic collections the update is atomic (either concurrent readers see the full result of the action or nothing).
    
    Parameters:
    action - the update action.
    
    Throws:
    
    ClassCastException - if the action type is not compatible with this collection (e.g. action on set and this is a list).
    See Also:
    perform(Consumer)
  - forEach
```
@Realtime(limit=LINEAR)
public void forEach(Consumer<? super E> consumer)
```
    Iterates over all this collection elements applying the specified consumer (convenience method). Iterations are performed concurrently if the collection is parallel.
    
    Parameters:
    consumer - the functional consumer applied to the collection elements.
  - removeIf
```
@Realtime(limit=LINEAR)
public boolean removeIf(Predicate<? super E> filter)
```
    Removes from this collection all the elements matching the specified functional predicate (convenience method). Removals are performed concurrently if this collection is parallel and atomically if this collection is atomic.
    
    Parameters:
    filter - a predicate returning true for elements to be removed.
    
    Returns:
    true if at least one element has been removed; false otherwise.
  - reduce
```
@Realtime(limit=LINEAR)
public E reduce(Reducer<E> reducer)
```
    Performs a reduction of the elements of this collection using the specified reducer. This may not involve iterating over all the collection elements, for example the reducers: Reducers.any(java.lang.Class<? extends E>), Reducers.and() and Reducers.or() may stop iterating early. Reduction is performed concurrently if this collection is parallel.
    
    Parameters:
    reducer - the collection reducer.
    
    Returns:
    the reduction result.
  - add
```
@Realtime(limit=LINEAR,
 comment="May have to search the whole collection (e.g. distinct view).")
public boolean add(E element)
```
    Adds the specified element to this collection
    
    Specified by:
    
    add in interface Collection<E>
  - isEmpty
```
@Realtime(limit=LINEAR,
 comment="May actually iterates the whole collection (e.g. filtered view).")
public boolean isEmpty()
```
    Indicates if this collection is empty.
    
    Specified by:
    
    isEmpty in interface Collection<E>
  - size
```
@Realtime(limit=LINEAR,
 comment="Potentially counts the elements.")
public int size()
```
    Returns the size of this collection.
    
    Specified by:
    
    size in interface Collection<E>
  - clear
```
@Realtime(limit=LINEAR,
 comment="Potentially removes elements one at a time.")
public void clear()
```
    Removes all elements from this collection.
    
    Specified by:
    
    clear in interface Collection<E>
  - contains
```
@Realtime(limit=LINEAR,
 comment="Potentially searches the whole collection.")
public boolean contains(Object searched)
```
    Indicates if this collection contains the specified element.
    
    Specified by:
    
    contains in interface Collection<E>
  - remove
```
@Realtime(limit=LINEAR,
 comment="Potentially searches the whole collection.")
public boolean remove(Object searched)
```
    Removes the specified element from this collection.
    
    Specified by:
    
    remove in interface Collection<E>
  - iterator
```
@Realtime(limit=N_SQUARE,
 comment="Construction of the iterator may require sorting the elements (e.g. sorted view)")
public Iterator<E> iterator()
```
    Returns an iterator over this collection elements. For shared/atomic collections the iterator is immune to concurrent modifications. In other words the elements iterated over may or may not reflect the current state of the collection.
    
    Specified by:
    
    iterator in interface Iterable<E>
    
    Specified by:
    
    iterator in interface Collection<E>
  - addAll
```
@Realtime(limit=LINEAR)
public boolean addAll(Collection<? extends E> that)
```
    Adds all the specified elements to this collection.
    
    Specified by:
    
    addAll in interface Collection<E>
  - containsAll
```
@Realtime(limit=N_SQUARE)
public boolean containsAll(Collection<?> that)
```
    Indicates if this collection contains all the specified elements.
    
    Specified by:
    
    containsAll in interface Collection<E>
  - removeAll
```
@Realtime(limit=N_SQUARE)
public boolean removeAll(Collection<?> that)
```
    Removes all the specified element from this collection.
    
    Specified by:
    
    removeAll in interface Collection<E>
  - retainAll
```
@Realtime(limit=N_SQUARE)
public boolean retainAll(Collection<?> that)
```
    Removes all the elements except those in the specified collection.
    
    Specified by:
    
    retainAll in interface Collection<E>
  - toArray
```
@Realtime(limit=LINEAR)
public Object[] toArray()
```
    Returns an array holding this collection elements.
    
    Specified by:
    
    toArray in interface Collection<E>
  - toArray
```
@Realtime(limit=LINEAR)
public <T> T[] toArray(T[] array)
```
    Returns the specified array holding this collection elements if enough capacity.
    
    Specified by:
    
    toArray in interface Collection<E>
  - any
```
@Realtime(limit=LINEAR)
public <T extends E> T any(Class<T> type)
```
    Returns any non-null element of the specified type (convenience method).
    
    Parameters:
    type - the element type searched for.
    
    Returns:
    reduce(Reducers.any(type))
    See Also:
    Reducers.any(java.lang.Class<? extends E>)
  - min
```
@Realtime(limit=LINEAR)
public E min()
```
    Returns the smallest element of this collection using this collection comparator (convenience method). Returns null if this collection is empty.
    
    Returns:
    reduce(Reducers.min(comparator()))
    See Also:
    Reducers.min(java.util.Comparator<? super E>)
  - max
```
@Realtime(limit=LINEAR)
public E max()
```
    Returns the largest element of this collection using this collection comparator (convenience method). Returns null if this collection is empty.
    
    Returns:
    reduce(Reducers.max(comparator()))
    See Also:
    Reducers.max(java.util.Comparator<? super E>)
  - addAll
```
@Realtime(limit=LINEAR)
public FastCollection<E> addAll(E... elements)
```
    Returns this collection with the specified element added.
    
    Parameters:
    elements - the elements to be added.
    
    Returns:
    this
  - addAll
```
@Realtime(limit=LINEAR)
public FastCollection<E> addAll(FastCollection<? extends E> that)
```
    Returns this collection with the specified collection's elements added in sequence.
  - comparator
```
@Realtime(limit=CONSTANT)
public Equality<? super E> comparator()
```
    Returns the comparator uses by this collection for equality and/or ordering if this collection is sorted.
  - toImmutable
```
@Realtime(limit=CONSTANT)
public <T extends Collection<E>> Immutable<T> toImmutable()
```
    Returns an immutable reference over this collection. The immutable value is an unmodifiable view of this collection. The caller must guarantees that the original collection is never going to be updated (e.g. there is no reference left of the original collection).
  - equals
```
@Realtime(limit=LINEAR)
public boolean equals(Object obj)
```
    Compares the specified object with this collection for equality. This method follows the Collection.equals(Object) specification if this collection comparator is Equalities.STANDARD (default). Otherwise, only collections using the same comparator can be considered equals.
    
    Specified by:
    
    equals in interface Collection<E>
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    obj - the object to be compared for equality with this collection
    
    Returns:
    true if both collections are considered equals; false otherwise.
  - hashCode
```
@Realtime(limit=LINEAR)
public int hashCode()
```
    Returns the hash code of this collection. This method follows the Collection.hashCode() specification if this collection comparator is Equalities.STANDARD.
    
    Specified by:
    
    hashCode in interface Collection<E>
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    this collection hash code.
  - toString
```
@Realtime(limit=LINEAR)
public String toString()
```
    Returns the string representation of this collection using its default format.
    
    Overrides:
    
    toString in class Object
  - service
```
protected abstract CollectionService<E> service()
```
    Returns the service implementation of this collection (for sub-classes).
  - serviceOf
```
protected static <E> CollectionService<E> serviceOf(FastCollection<E> collection)
```
    Returns the service implementation of any fast collection (for sub-classes).

All Classes

Summary:
Nested |
Field |
Constr |
Method

Detail:
Field |
Constr |
Method

Class FastCollection<E>

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

FastCollection

Method Detail

atomic

shared

parallel

sequential

unmodifiable

filtered

mapped

sorted

sorted

reversed

distinct

perform

update

forEach

removeIf

reduce

add

isEmpty

size

clear

contains

remove

iterator

addAll

containsAll

removeAll

retainAll

toArray

toArray

any

min

max

addAll

addAll

comparator

toImmutable

equals

hashCode

toString

service

serviceOf