Package org.eclipse.collections.api.collection

Interface ImmutableCollection<T>

All Superinterfaces:
InternalIterable<T>, Iterable<T>, RichIterable<T>
All Known Subinterfaces:
ImmutableBag<T>, ImmutableBagIterable<T>, ImmutableList<T>, ImmutableSet<T>, ImmutableSetIterable<T>, ImmutableSortedBag<T>, ImmutableSortedSet<T>
All Known Implementing Classes:
AbstractImmutableBag, AbstractImmutableBagIterable, AbstractImmutableCollection, AbstractImmutableSet, ImmutableArrayBag, ImmutableHashBag
public interface ImmutableCollection<T>
extends RichIterable<T>
ImmutableCollection is the common interface between ImmutableList, ImmutableSet and ImmutableBag. The ImmutableCollection interface is "contractually immutable" in that it does not have any mutating methods available on the public interface.

  • Method Details

    • newWith

      ImmutableCollection<T> newWith​(T element)
      This method is similar to the with method in MutableCollection with the difference that a new copy of this collection with the element appended will be returned.

    • newWithout

      ImmutableCollection<T> newWithout​(T element)
      This method is similar to the without method in MutableCollection with the difference that a new copy of this collection with the element removed will be returned.

    • newWithAll

      ImmutableCollection<T> newWithAll​(Iterable<? extends T> elements)
      This method is similar to the withAll method in MutableCollection with the difference that a new copy of this collection with the elements appended will be returned.

    • newWithoutAll

      ImmutableCollection<T> newWithoutAll​(Iterable<? extends T> elements)
      This method is similar to the withoutAll method in MutableCollection with the difference that a new copy of this collection with the elements removed will be returned.

    • tap

      ImmutableCollection<T> tap​(Procedure<? super T> procedure)
      Description copied from interface: RichIterable
      Executes the Procedure for each element in the iterable and returns this.

      Example using a Java 8 lambda expression: 

       RichIterable<Person> tapped =
     people.tap(person -> LOGGER.info(person.getName()));

      Example using an anonymous inner class: 

       RichIterable<Person> tapped =
     people.tap(new Procedure<Person>()
     {
         public void value(Person person)
         {
             LOGGER.info(person.getName());
         }
     });
      Specified by:
      tap in interface RichIterable<T>
      See Also:
      RichIterable.each(Procedure), RichIterable.forEach(Procedure)

    • select

      ImmutableCollection<T> select​(Predicate<? super T> predicate)
      Description copied from interface: RichIterable
      Returns all elements of the source collection that return true when evaluating the predicate. This method is also commonly called filter.

      Example using a Java 8 lambda expression: 

       RichIterable<Person> selected =
     people.select(person -> person.getAddress().getCity().equals("London"));

      Example using an anonymous inner class: 

       RichIterable<Person> selected =
     people.select(new Predicate<Person>()
     {
         public boolean accept(Person person)
         {
             return person.getAddress().getCity().equals("London");
         }
     });
      Specified by:
      select in interface RichIterable<T>

    • selectWith

      <P> ImmutableCollection<T> selectWith​(Predicate2<? super T,​? super P> predicate, P parameter)
      Description copied from interface: RichIterable
      Similar to RichIterable.select(Predicate), except with an evaluation parameter for the second generic argument in Predicate2.

      E.g. return a Collection of Person elements where the person has an age greater than or equal to 18 years

      Example using a Java 8 lambda expression: 

       RichIterable<Person> selected =
     people.selectWith((Person person, Integer age) -> person.getAge()>= age, Integer.valueOf(18));

      Example using an anonymous inner class: 

       RichIterable<Person> selected =
     people.selectWith(new Predicate2<Person, Integer>()
     {
         public boolean accept(Person person, Integer age)
         {
             return person.getAge()>= age;
         }
     }, Integer.valueOf(18));
      Specified by:
      selectWith in interface RichIterable<T>
      Parameters:
      predicate - a Predicate2 to use as the select criteria
      parameter - a parameter to pass in for evaluation of the second argument P in predicate
      See Also:
      RichIterable.select(Predicate)

    • reject

      ImmutableCollection<T> reject​(Predicate<? super T> predicate)
      Description copied from interface: RichIterable
      Returns all elements of the source collection that return false when evaluating of the predicate. This method is also sometimes called filterNot and is the equivalent of calling iterable.select(Predicates.not(predicate)).

      Example using a Java 8 lambda expression: 

       RichIterable<Person> rejected =
     people.reject(person -> person.person.getLastName().equals("Smith"));

      Example using an anonymous inner class: 

       RichIterable<Person> rejected =
     people.reject(new Predicate<Person>()
     {
         public boolean accept(Person person)
         {
             return person.person.getLastName().equals("Smith");
         }
     });
      Specified by:
      reject in interface RichIterable<T>
      Parameters:
      predicate - a Predicate to use as the reject criteria
      Returns:
      a RichIterable that contains elements that cause Predicate.accept(Object) method to evaluate to false

    • rejectWith

      <P> ImmutableCollection<T> rejectWith​(Predicate2<? super T,​? super P> predicate, P parameter)
      Description copied from interface: RichIterable
      Similar to RichIterable.reject(Predicate), except with an evaluation parameter for the second generic argument in Predicate2.

      E.g. return a Collection of Person elements where the person has an age greater than or equal to 18 years

      Example using a Java 8 lambda expression: 

       RichIterable<Person> rejected =
     people.rejectWith((Person person, Integer age) -> person.getAge() < age, Integer.valueOf(18));

      Example using an anonymous inner class: 

       MutableList<Person> rejected =
     people.rejectWith(new Predicate2<Person, Integer>()
     {
         public boolean accept(Person person, Integer age)
         {
             return person.getAge() < age;
         }
     }, Integer.valueOf(18));
      Specified by:
      rejectWith in interface RichIterable<T>
      Parameters:
      predicate - a Predicate2 to use as the select criteria
      parameter - a parameter to pass in for evaluation of the second argument P in predicate
      See Also:
      RichIterable.select(Predicate)

    • partition

      PartitionImmutableCollection<T> partition​(Predicate<? super T> predicate)
      Description copied from interface: RichIterable
      Filters a collection into a PartitionedIterable based on the evaluation of the predicate.

      Example using a Java 8 lambda expression: 

       PartitionIterable<Person> newYorkersAndNonNewYorkers =
     people.partition(person -> person.getAddress().getState().getName().equals("New York"));

      Example using an anonymous inner class: 

       PartitionIterable<Person> newYorkersAndNonNewYorkers =
     people.partition(new Predicate<Person>()
     {
         public boolean accept(Person person)
         {
             return person.getAddress().getState().getName().equals("New York");
         }
     });
      Specified by:
      partition in interface RichIterable<T>

    • partitionWith

      <P> PartitionImmutableCollection<T> partitionWith​(Predicate2<? super T,​? super P> predicate, P parameter)
      Description copied from interface: RichIterable
      Filters a collection into a PartitionIterable based on the evaluation of the predicate.

      Example using a Java 8 lambda expression: 

       PartitionIterable<Person> newYorkersAndNonNewYorkers =
     people.partitionWith((Person person, String state) -> person.getAddress().getState().getName().equals(state), "New York");

      Example using an anonymous inner class: 

       PartitionIterable<Person> newYorkersAndNonNewYorkers =
     people.partitionWith(new Predicate2<Person, String>()
     {
         public boolean accept(Person person, String state)
         {
             return person.getAddress().getState().getName().equals(state);
         }
     }, "New York");
      Specified by:
      partitionWith in interface RichIterable<T>

    • selectInstancesOf

      <S> ImmutableCollection<S> selectInstancesOf​(Class<S> clazz)
      Description copied from interface: RichIterable
      Returns all elements of the source collection that are instances of the Class clazz. 
       RichIterable<Integer> integers =
     List.mutable.with(new Integer(0), new Long(0L), new Double(0.0)).selectInstancesOf(Integer.class);
      Specified by:
      selectInstancesOf in interface RichIterable<T>

    • collect

      <V> ImmutableCollection<V> collect​(Function<? super T,​? extends V> function)
      Description copied from interface: RichIterable
      Returns a new collection with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       RichIterable<String> names =
     people.collect(person -> person.getFirstName() + " " + person.getLastName());

      Example using an anonymous inner class: 

       RichIterable<String> names =
     people.collect(new Function<Person, String>()
     {
         public String valueOf(Person person)
         {
             return person.getFirstName() + " " + person.getLastName();
         }
     });
      Specified by:
      collect in interface RichIterable<T>

    • collectBoolean

      ImmutableBooleanCollection collectBoolean​(BooleanFunction<? super T> booleanFunction)
      Description copied from interface: RichIterable
      Returns a new primitive boolean iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       BooleanIterable licenses =
     people.collectBoolean(person -> person.hasDrivingLicense());

      Example using an anonymous inner class: 

       BooleanIterable licenses =
     people.collectBoolean(new BooleanFunction<Person>()
     {
         public boolean booleanValueOf(Person person)
         {
             return person.hasDrivingLicense();
         }
     });
      Specified by:
      collectBoolean in interface RichIterable<T>

    • collectByte

      ImmutableByteCollection collectByte​(ByteFunction<? super T> byteFunction)
      Description copied from interface: RichIterable
      Returns a new primitive byte iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       ByteIterable bytes =
     people.collectByte(person -> person.getCode());

      Example using an anonymous inner class: 

       ByteIterable bytes =
     people.collectByte(new ByteFunction<Person>()
     {
         public byte byteValueOf(Person person)
         {
             return person.getCode();
         }
     });
      Specified by:
      collectByte in interface RichIterable<T>

    • collectChar

      ImmutableCharCollection collectChar​(CharFunction<? super T> charFunction)
      Description copied from interface: RichIterable
      Returns a new primitive char iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       CharIterable chars =
     people.collectChar(person -> person.getMiddleInitial());

      Example using an anonymous inner class: 

       CharIterable chars =
     people.collectChar(new CharFunction<Person>()
     {
         public char charValueOf(Person person)
         {
             return person.getMiddleInitial();
         }
     });
      Specified by:
      collectChar in interface RichIterable<T>

    • collectDouble

      ImmutableDoubleCollection collectDouble​(DoubleFunction<? super T> doubleFunction)
      Description copied from interface: RichIterable
      Returns a new primitive double iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       DoubleIterable doubles =
     people.collectDouble(person -> person.getMilesFromNorthPole());

      Example using an anonymous inner class: 

       DoubleIterable doubles =
     people.collectDouble(new DoubleFunction<Person>()
     {
         public double doubleValueOf(Person person)
         {
             return person.getMilesFromNorthPole();
         }
     });
      Specified by:
      collectDouble in interface RichIterable<T>

    • collectFloat

      ImmutableFloatCollection collectFloat​(FloatFunction<? super T> floatFunction)
      Description copied from interface: RichIterable
      Returns a new primitive float iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       FloatIterable floats =
     people.collectFloat(person -> person.getHeightInInches());

      Example using an anonymous inner class: 

       FloatIterable floats =
     people.collectFloat(new FloatFunction<Person>()
     {
         public float floatValueOf(Person person)
         {
             return person.getHeightInInches();
         }
     });
      Specified by:
      collectFloat in interface RichIterable<T>

    • collectInt

      ImmutableIntCollection collectInt​(IntFunction<? super T> intFunction)
      Description copied from interface: RichIterable
      Returns a new primitive int iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       IntIterable ints =
     people.collectInt(person -> person.getAge());

      Example using an anonymous inner class: 

       IntIterable ints =
     people.collectInt(new IntFunction<Person>()
     {
         public int intValueOf(Person person)
         {
             return person.getAge();
         }
     });
      Specified by:
      collectInt in interface RichIterable<T>

    • collectLong

      ImmutableLongCollection collectLong​(LongFunction<? super T> longFunction)
      Description copied from interface: RichIterable
      Returns a new primitive long iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       LongIterable longs =
     people.collectLong(person -> person.getGuid());

      Example using an anonymous inner class: 

       LongIterable longs =
     people.collectLong(new LongFunction<Person>()
     {
         public long longValueOf(Person person)
         {
             return person.getGuid();
         }
     });
      Specified by:
      collectLong in interface RichIterable<T>

    • collectShort

      ImmutableShortCollection collectShort​(ShortFunction<? super T> shortFunction)
      Description copied from interface: RichIterable
      Returns a new primitive short iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       ShortIterable shorts =
     people.collectShort(person -> person.getNumberOfJunkMailItemsReceivedPerMonth());

      Example using an anonymous inner class: 

       ShortIterable shorts =
     people.collectShort(new ShortFunction<Person>()
     {
         public short shortValueOf(Person person)
         {
             return person.getNumberOfJunkMailItemsReceivedPerMonth();
         }
     });
      Specified by:
      collectShort in interface RichIterable<T>

    • collectWith

      <P,​ V> ImmutableCollection<V> collectWith​(Function2<? super T,​? super P,​? extends V> function, P parameter)
      Description copied from interface: RichIterable
      Same as RichIterable.collect(Function) with a Function2 and specified parameter which is passed to the block.

      Example using a Java 8 lambda expression: 

       RichIterable<Integer> integers =
     Lists.mutable.with(1, 2, 3).collectWith((each, parameter) -> each + parameter, Integer.valueOf(1));

      Example using an anonymous inner class: 

       Function2<Integer, Integer, Integer> addParameterFunction =
     new Function2<Integer, Integer, Integer>()
     {
         public Integer value(Integer each, Integer parameter)
         {
             return each + parameter;
         }
     };
 RichIterable<Integer> integers =
     Lists.mutable.with(1, 2, 3).collectWith(addParameterFunction, Integer.valueOf(1));
      Specified by:
      collectWith in interface RichIterable<T>
      Parameters:
      function - A Function2 to use as the collect transformation function
      parameter - A parameter to pass in for evaluation of the second argument P in function
      Returns:
      A new RichIterable that contains the transformed elements returned by Function2.value(Object, Object)
      See Also:
      RichIterable.collect(Function)

    • collectIf

      <V> ImmutableCollection<V> collectIf​(Predicate<? super T> predicate, Function<? super T,​? extends V> function)
      Description copied from interface: RichIterable
      Returns a new collection with the results of applying the specified function on each element of the source collection, but only for those elements which return true upon evaluation of the predicate. This is the the optimized equivalent of calling iterable.select(predicate).collect(function).

      Example using a Java 8 lambda and method reference: 

       RichIterable<String> strings = Lists.mutable.with(1, 2, 3).collectIf(e -> e != null, Object::toString);

      Example using Predicates factory: 

       RichIterable<String> strings = Lists.mutable.with(1, 2, 3).collectIf(Predicates.notNull(), Functions.getToString());
      Specified by:
      collectIf in interface RichIterable<T>

    • flatCollect

      <V> ImmutableCollection<V> flatCollect​(Function<? super T,​? extends Iterable<V>> function)
      Description copied from interface: RichIterable
      flatCollect is a special case of RichIterable.collect(Function). With collect, when the Function returns a collection, the result is a collection of collections. flatCollect outputs a single "flattened" collection instead. This method is commonly called flatMap.

      Consider the following example where we have a Person class, and each Person has a list of Address objects. Take the following Function: 

       Function<Person, List<Address>> addressFunction = Person::getAddresses;
 RichIterable<Person> people = ...;
      Using collect returns a collection of collections of addresses. 
       RichIterable<List<Address>> addresses = people.collect(addressFunction);
      Using flatCollect returns a single flattened list of addresses. 
       RichIterable<Address> addresses = people.flatCollect(addressFunction);
      Specified by:
      flatCollect in interface RichIterable<T>
      Parameters:
      function - The Function to apply
      Returns:
      a new flattened collection produced by applying the given function

    • flatCollectWith

      default <P,​ V> ImmutableCollection<V> flatCollectWith​(Function2<? super T,​? super P,​? extends Iterable<V>> function, P parameter)
      Specified by:
      flatCollectWith in interface RichIterable<T>
      Since:
      9.2

    • sumByInt

      <V> ImmutableObjectLongMap<V> sumByInt​(Function<? super T,​? extends V> groupBy, IntFunction<? super T> function)
      Description copied from interface: RichIterable
      Groups and sums the values using the two specified functions.
      Specified by:
      sumByInt in interface RichIterable<T>

    • sumByFloat

      <V> ImmutableObjectDoubleMap<V> sumByFloat​(Function<? super T,​? extends V> groupBy, FloatFunction<? super T> function)
      Description copied from interface: RichIterable
      Groups and sums the values using the two specified functions.
      Specified by:
      sumByFloat in interface RichIterable<T>

    • sumByLong

      <V> ImmutableObjectLongMap<V> sumByLong​(Function<? super T,​? extends V> groupBy, LongFunction<? super T> function)
      Description copied from interface: RichIterable
      Groups and sums the values using the two specified functions.
      Specified by:
      sumByLong in interface RichIterable<T>

    • sumByDouble

      <V> ImmutableObjectDoubleMap<V> sumByDouble​(Function<? super T,​? extends V> groupBy, DoubleFunction<? super T> function)
      Description copied from interface: RichIterable
      Groups and sums the values using the two specified functions.
      Specified by:
      sumByDouble in interface RichIterable<T>

    • countBy

      default <V> ImmutableBag<V> countBy​(Function<? super T,​? extends V> function)
      Description copied from interface: RichIterable
      This method will count the number of occurrences of each value calculated by applying the function to each element of the collection.
      Specified by:
      countBy in interface RichIterable<T>
      Since:
      9.0

    • countByWith

      default <V,​ P> ImmutableBag<V> countByWith​(Function2<? super T,​? super P,​? extends V> function, P parameter)
      Description copied from interface: RichIterable
      This method will count the number of occurrences of each value calculated by applying the function to each element of the collection with the specified parameter as the second argument.
      Specified by:
      countByWith in interface RichIterable<T>
      Since:
      9.0

    • countByEach

      default <V> ImmutableBag<V> countByEach​(Function<? super T,​? extends Iterable<V>> function)
      Description copied from interface: RichIterable
      This method will count the number of occurrences of each value calculated by applying the function to each element of the collection.
      Specified by:
      countByEach in interface RichIterable<T>
      Since:
      10.0.0

    • groupBy

      <V> ImmutableMultimap<V,​T> groupBy​(Function<? super T,​? extends V> function)
      Description copied from interface: RichIterable
      For each element of the iterable, the function is evaluated and the results of these evaluations are collected into a new multimap, where the transformed value is the key and the original values are added to the same (or similar) species of collection as the source iterable.

      Example using a Java 8 method reference: 

       Multimap<String, Person> peopleByLastName =
     people.groupBy(Person::getLastName);

      Example using an anonymous inner class: 

       Multimap<String, Person> peopleByLastName =
     people.groupBy(new Function<Person, String>()
     {
         public String valueOf(Person person)
         {
             return person.getLastName();
         }
     });
      Specified by:
      groupBy in interface RichIterable<T>

    • groupByEach

      <V> ImmutableMultimap<V,​T> groupByEach​(Function<? super T,​? extends Iterable<V>> function)
      Description copied from interface: RichIterable
      Similar to RichIterable.groupBy(Function), except the result of evaluating function will return a collection of keys for each value.
      Specified by:
      groupByEach in interface RichIterable<T>

    • groupByUniqueKey

      default <V> ImmutableMap<V,​T> groupByUniqueKey​(Function<? super T,​? extends V> function)
      Description copied from interface: RichIterable
      For each element of the iterable, the function is evaluated and he results of these evaluations are collected into a new map, where the transformed value is the key. The generated keys must each be unique, or else an exception is thrown.
      Specified by:
      groupByUniqueKey in interface RichIterable<T>
      See Also:
      RichIterable.groupBy(Function)

    • zip

      <S> ImmutableCollection<Pair<T,​S>> zip​(Iterable<S> that)
      Description copied from interface: RichIterable
      Returns a RichIterable formed from this RichIterable and another RichIterable by combining corresponding elements in pairs. If one of the two RichIterables is longer than the other, its remaining elements are ignored.
      Specified by:
      zip in interface RichIterable<T>
      Type Parameters:
      S - the type of the second half of the returned pairs
      Parameters:
      that - The RichIterable providing the second half of each result pair
      Returns:
      A new RichIterable containing pairs consisting of corresponding elements of this RichIterable and that. The length of the returned RichIterable is the minimum of the lengths of this RichIterable and that.

    • zipWithIndex

      ImmutableCollection<Pair<T,​Integer>> zipWithIndex()
      Description copied from interface: RichIterable
      Zips this RichIterable with its indices.
      Specified by:
      zipWithIndex in interface RichIterable<T>
      Returns:
      A new RichIterable containing pairs consisting of all elements of this RichIterable paired with their index. Indices start at 0.
      See Also:
      RichIterable.zip(Iterable)

    • aggregateInPlaceBy

      default <K,​ V> ImmutableMap<K,​V> aggregateInPlaceBy​(Function<? super T,​? extends K> groupBy, Function0<? extends V> zeroValueFactory, Procedure2<? super V,​? super T> mutatingAggregator)
      Description copied from interface: RichIterable
      Applies an aggregate procedure over the iterable grouping results into a Map based on the specific groupBy function. Aggregate results are required to be mutable as they will be changed in place by the procedure. A second function specifies the initial "zero" aggregate value to work with (i.e. new AtomicInteger(0)).
      Specified by:
      aggregateInPlaceBy in interface RichIterable<T>

    • aggregateBy

      default <K,​ V> ImmutableMap<K,​V> aggregateBy​(Function<? super T,​? extends K> groupBy, Function0<? extends V> zeroValueFactory, Function2<? super V,​? super T,​? extends V> nonMutatingAggregator)
      Description copied from interface: RichIterable
      Applies an aggregate function over the iterable grouping results into a map based on the specific groupBy function. Aggregate results are allowed to be immutable as they will be replaced in place in the map. A second function specifies the initial "zero" aggregate value to work with (i.e. Integer.valueOf(0)).
      Specified by:
      aggregateBy in interface RichIterable<T>

    • stream

      default Stream<T> stream()
      Since:
      9.0

    • parallelStream

      default Stream<T> parallelStream()
      Since:
      9.0

    • spliterator

      default Spliterator<T> spliterator()
      Specified by:
      spliterator in interface Iterable<T>
      Since:
      9.0

    • castToCollection

      Collection<T> castToCollection()
      This can be overridden in most implementations to just return this.
      Since:
      9.0