Package org.eclipse.collections.api.bimap

Interface BiMap<K,​V>

All Superinterfaces:
InternalIterable<V>, Iterable<V>, MapIterable<K,​V>, RichIterable<V>
All Known Subinterfaces:
ImmutableBiMap<K,​V>, MutableBiMap<K,​V>
All Known Implementing Classes:
AbstractBiMap, AbstractImmutableBiMap, HashBiMap, SynchronizedBiMap, UnmodifiableBiMap
public interface BiMap<K,​V>
extends MapIterable<K,​V>
A map that allows users to look up key-value pairs from either direction. Uniqueness is enforced on both the keys and values.
Since:
4.2

  • Method Details

    • inverse

      BiMap<V,​K> inverse()
      Returns an inversed view of this BiMap, where the associations are in the direction of this bimap's values to keys.

    • flip

      SetMultimap<V,​K> flip()
      Description copied from interface: MapIterable
      Given a map from Domain -> Range return a multimap from Range -> Domain. We chose the name 'flip' rather than 'invert' or 'transpose' since this method does not have the property of applying twice returns the original.

      Since the keys in the input are unique, the values in the output are unique, so the return type should be a SetMultimap. However since SetMultimap and SortedSetMultimap don't inherit from one another, SetMultimap here does not allow SortedMapIterable to have a SortedSetMultimap return. Thus we compromise and call this Multimap, even though all implementations will be a SetMultimap or SortedSetMultimap.

      Specified by:
      flip in interface MapIterable<K,​V>

    • flipUniqueValues

      BiMap<V,​K> flipUniqueValues()
      Description copied from interface: MapIterable
      Return the MapIterable that is obtained by flipping the direction of this map and making the associations from value to key. 
           MapIterable<Integer, String> map = this.newMapWithKeysValues(1, "1", 2, "2", 3, "3");
     MapIterable<String, Integer> result = map.flipUniqueValues();
     Assert.assertTrue(result.equals(UnifiedMap.newWithKeysValues("1", 1, "2", 2, "3", 3)));
      Specified by:
      flipUniqueValues in interface MapIterable<K,​V>

    • toImmutable

      ImmutableBiMap<K,​V> toImmutable()
      Converts the BiMap to an ImmutableBiMap. If the bimap is immutable, it returns itself.
      Specified by:
      toImmutable in interface MapIterable<K,​V>

    • tap

      BiMap<K,​V> tap​(Procedure<? super V> procedure)
      Description copied from interface: MapIterable
      Executes the Procedure for each value of the map and returns this. 
       return peopleByCity.tap(person -> LOGGER.info(person.getName()));
      Specified by:
      tap in interface MapIterable<K,​V>
      Specified by:
      tap in interface RichIterable<K>
      See Also:
      RichIterable.forEach(Procedure)

    • select

      BiMap<K,​V> select​(Predicate2<? super K,​? super V> predicate)
      Description copied from interface: MapIterable
      For each key and value of the map the predicate is evaluated, if the result of the evaluation is true, that key and value are returned in a new map. 
       MapIterable<City, Person> selected =
     peopleByCity.select((city, person) -> city.getName().equals("Anytown") && person.getLastName().equals("Smith"));
      Specified by:
      select in interface MapIterable<K,​V>

    • reject

      BiMap<K,​V> reject​(Predicate2<? super K,​? super V> predicate)
      Description copied from interface: MapIterable
      For each key and value of the map the predicate is evaluated, if the result of the evaluation is false, that key and value are returned in a new map. 
       MapIterable<City, Person> rejected =
     peopleByCity.reject((city, person) -> city.getName().equals("Anytown") && person.getLastName().equals("Smith"));
      Specified by:
      reject in interface MapIterable<K,​V>

    • collect

      <K2,​ V2> BiMap<K2,​V2> collect​(Function2<? super K,​? super V,​Pair<K2,​V2>> function)
      For each key and value of the map the function is evaluated. The results of these evaluations are returned in a new map. The map returned will use the values projected from the function rather than the original values. 
       MapIterable<String, String> collected =
     peopleByCity.collect((City city, Person person) -> Pair.of(city.getCountry(), person.getAddress().getCity()));
      Implementations are expected to delegate to MutableBiMap.put(Object, Object), ImmutableBiMap.newWithKeyValue(Object, Object), or equivalent, not MutableBiMap.forcePut(Object, Object).
      Specified by:
      collect in interface MapIterable<K,​V>
      Throws:
      RuntimeException - when function returns colliding keys or values.

    • collectValues

      <R> BiMap<K,​R> collectValues​(Function2<? super K,​? super V,​? extends R> function)
      For each key and value of the map the function is evaluated. The results of these evaluations are returned in a new map. The map returned will use the values projected from the function rather than the original values. 
       MapIterable<City, String> collected =
     peopleByCity.collectValues((City city, Person person) -> person.getFirstName() + " " + person.getLastName());
      Implementations are expected to delegate to MutableBiMap.put(Object, Object), ImmutableBiMap.newWithKeyValue(Object, Object), or equivalent, not MutableBiMap.forcePut(Object, Object).
      Specified by:
      collectValues in interface MapIterable<K,​V>
      Throws:
      RuntimeException - when function returns colliding values.

    • select

      SetIterable<V> select​(Predicate<? super V> 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<K>

    • selectWith

      <P> SetIterable<V> selectWith​(Predicate2<? super V,​? 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<K>
      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

      SetIterable<V> reject​(Predicate<? super V> 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<K>
      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> SetIterable<V> rejectWith​(Predicate2<? super V,​? 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<K>
      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

      PartitionUnsortedSet<V> partition​(Predicate<? super V> 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<K>

    • partitionWith

      <P> PartitionUnsortedSet<V> partitionWith​(Predicate2<? super V,​? 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<K>

    • selectInstancesOf

      <S> SetIterable<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<K>

    • zip

      @Deprecated <S> SetIterable<Pair<V,​S>> zip​(Iterable<S> that)
      Deprecated.
      in 8.0. Use OrderedIterable.zip(Iterable) instead.
      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<K>
      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

      @Deprecated SetIterable<Pair<V,​Integer>> zipWithIndex()
      Deprecated.
      in 8.0. Use OrderedIterable.zipWithIndex() instead.
      Description copied from interface: RichIterable
      Zips this RichIterable with its indices.
      Specified by:
      zipWithIndex in interface RichIterable<K>
      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)

    • groupBy

      <V1> SetMultimap<V1,​V> groupBy​(Function<? super V,​? extends V1> 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<K>

    • groupByEach

      <V1> SetMultimap<V1,​V> groupByEach​(Function<? super V,​? extends Iterable<V1>> 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<K>

    • groupByUniqueKey

      <VV> BiMap<VV,​V> groupByUniqueKey​(Function<? super V,​? extends VV> 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<K>
      See Also:
      RichIterable.groupBy(Function)