Bag (Eclipse Collections

All Superinterfaces:

InternalIterable<T>, java.lang.Iterable<T>, RichIterable<T>

All Known Subinterfaces:

ImmutableBag<T>, ImmutableBagIterable<T>, ImmutableSortedBag<T>, MutableBag<T>, MutableBagIterable<T>, MutableSortedBag<T>, SortedBag<T>, UnsortedBag<T>

All Known Implementing Classes:

AbstractBag, AbstractHashBag, AbstractImmutableBag, AbstractImmutableBagIterable, AbstractMutableBag, AbstractMutableBagIterable, AbstractMutableSortedBag, HashBag, HashBagWithHashingStrategy, ImmutableArrayBag, ImmutableHashBag, MultiReaderHashBag, SynchronizedBag, SynchronizedSortedBag, TreeBag, UnmodifiableBag, UnmodifiableSortedBag
```
public interface Bag<T>
extends RichIterable<T>
```
A Bag is a Collection whose elements are unordered and may contain duplicate entries. It varies from MutableCollection in that it adds a protocol for determining, adding, and removing the number of occurrences for an item.

Since:

1.0

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`ListIterable<ObjectIntPair<T>>`	`bottomOccurrences(int count)`	Returns the `count` least frequently occurring items.
`default <V,R extends java.util.Collection<V>> R`	`collectWithOccurrences(ObjectIntToObjectFunction<? super T,? extends V> function, R target)`	Iterates over the unique elements and their occurrences and collects the results of applying the specified function into the target collection.
`boolean`	`equals(java.lang.Object object)`	Two bags`b1` and `b2` are equal if `m1.toMapOfItemToCount().equals(m2.toMapOfItemToCount())`.
`void`	`forEachWithOccurrences(ObjectIntProcedure<? super T> procedure)`	For each distinct item, with the number of occurrences, execute the specified procedure.
`<V> BagMultimap<V,T>`	`groupBy(Function<? super T,? extends V> function)`	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.
`<V> BagMultimap<V,T>`	`groupByEach(Function<? super T,? extends java.lang.Iterable<V>> function)`	Similar to `RichIterable.groupBy(Function)`, except the result of evaluating function will return a collection of keys for each value.
`int`	`hashCode()`	Returns the hash code for this Bag, defined as `this.toMapOfItemToCount().hashCode()`.
`int`	`occurrencesOf(java.lang.Object item)`	The occurrences of a distinct item in the bag.
`PartitionBag<T>`	`partition(Predicate<? super T> predicate)`	Filters a collection into a PartitionedIterable based on the evaluation of the predicate.
`<P> PartitionBag<T>`	`partitionWith(Predicate2<? super T,? super P> predicate, P parameter)`	Filters a collection into a PartitionIterable based on the evaluation of the predicate.
`default <R> R`	`reduceInPlace(java.util.function.Supplier<R> supplier, java.util.function.BiConsumer<R,? super T> accumulator)`	This method produces the equivalent result as `Stream.collect(Supplier, BiConsumer, BiConsumer)`.
`default <R,A> R`	`reduceInPlace(java.util.stream.Collector<? super T,A,R> collector)`	This method produces the equivalent result as `Stream.collect(Collector)`.
`Bag<T>`	`reject(Predicate<? super T> predicate)`	Returns all elements of the source collection that return false when evaluating of the predicate.
`<P> Bag<T>`	`rejectWith(Predicate2<? super T,? super P> predicate, P parameter)`	Similar to `RichIterable.reject(Predicate)`, except with an evaluation parameter for the second generic argument in `Predicate2`.
`Bag<T>`	`select(Predicate<? super T> predicate)`	Returns all elements of the source collection that return true when evaluating the predicate.
`Bag<T>`	`selectByOccurrences(IntPredicate predicate)`	Returns all elements of the bag that have a number of occurrences that satisfy the predicate.
`default Bag<T>`	`selectDuplicates()`	Returns all elements of the bag that have more than one occurrence.
`<S> Bag<S>`	`selectInstancesOf(java.lang.Class<S> clazz)`	Returns all elements of the source collection that are instances of the Class `clazz`.
`default SetIterable<T>`	`selectUnique()`	Returns a set containing all elements of the bag that have exactly one occurrence.
`<P> Bag<T>`	`selectWith(Predicate2<? super T,? super P> predicate, P parameter)`	Similar to `RichIterable.select(Predicate)`, except with an evaluation parameter for the second generic argument in `Predicate2`.
`int`	`sizeDistinct()`	The size of the Bag when counting only distinct elements.
`default java.util.DoubleSummaryStatistics`	`summarizeDouble(DoubleFunction<? super T> function)`	Returns the result of summarizing the value returned from applying the DoubleFunction to each element of the iterable.
`default java.util.DoubleSummaryStatistics`	`summarizeFloat(FloatFunction<? super T> function)`	Returns the result of summarizing the value returned from applying the FloatFunction to each element of the iterable.
`default java.util.IntSummaryStatistics`	`summarizeInt(IntFunction<? super T> function)`	Returns the result of summarizing the value returned from applying the IntFunction to each element of the iterable.
`default java.util.LongSummaryStatistics`	`summarizeLong(LongFunction<? super T> function)`	Returns the result of summarizing the value returned from applying the LongFunction to each element of the iterable.
`Bag<T>`	`tap(Procedure<? super T> procedure)`	Executes the Procedure for each element in the iterable and returns `this`.
`ImmutableBagIterable<T>`	`toImmutable()`
`MapIterable<T,java.lang.Integer>`	`toMapOfItemToCount()`	Converts the Bag to a Map of the Item type to its count as an Integer.
`ListIterable<ObjectIntPair<T>>`	`topOccurrences(int count)`	Returns the `count` most frequently occurring items.
`java.lang.String`	`toStringOfItemToCount()`	Returns a string representation of this bag.
`SetIterable<Pair<T,java.lang.Integer>>`	`zipWithIndex()`	Zips this `RichIterable` with its indices.

Methods inherited from interface org.eclipse.collections.api.InternalIterable
forEach, forEach, forEachWith, forEachWithIndex

Methods inherited from interface java.lang.Iterable
iterator, spliterator

Methods inherited from interface org.eclipse.collections.api.RichIterable
aggregateBy, aggregateInPlaceBy, allSatisfy, allSatisfyWith, anySatisfy, anySatisfyWith, appendString, appendString, appendString, asLazy, chunk, collect, collect, collectBoolean, collectBoolean, collectByte, collectByte, collectChar, collectChar, collectDouble, collectDouble, collectFloat, collectFloat, collectIf, collectIf, collectInt, collectInt, collectLong, collectLong, collectShort, collectShort, collectWith, collectWith, contains, containsAll, containsAllArguments, containsAllIterable, count, countBy, countBy, countByWith, countByWith, countWith, detect, detectIfNone, detectOptional, detectWith, detectWithIfNone, detectWithOptional, each, flatCollect, flatCollect, flatCollectWith, flatCollectWith, getFirst, getLast, getOnly, groupBy, groupByEach, groupByUniqueKey, groupByUniqueKey, injectInto, injectInto, injectInto, injectInto, injectInto, into, isEmpty, makeString, makeString, makeString, max, max, maxBy, maxByOptional, maxOptional, maxOptional, min, min, minBy, minByOptional, minOptional, minOptional, noneSatisfy, noneSatisfyWith, notEmpty, reduce, reject, rejectWith, select, selectWith, size, sumByDouble, sumByFloat, sumByInt, sumByLong, sumOfDouble, sumOfFloat, sumOfInt, sumOfLong, toArray, toArray, toBag, toList, toMap, toSet, toSortedBag, toSortedBag, toSortedBagBy, toSortedList, toSortedList, toSortedListBy, toSortedMap, toSortedMap, toSortedMapBy, toSortedSet, toSortedSet, toSortedSetBy, toString, zip, zip, zipWithIndex

- Method Detail
  - equals
```
boolean equals(java.lang.Object object)
```
    Two bagsb1 and b2 are equal if m1.toMapOfItemToCount().equals(m2.toMapOfItemToCount()).
    
    Overrides:
    
    equals in class java.lang.Object
    
    See Also:
    
    Map.equals(Object)
  - hashCode
```
int hashCode()
```
    Returns the hash code for this Bag, defined as this.toMapOfItemToCount().hashCode().
    
    Overrides:
    
    hashCode in class java.lang.Object
    
    See Also:
    
    Map.hashCode()
  - tap
```
Bag<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), InternalIterable.forEach(Procedure)
  - select
```
Bag<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> Bag<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
```
Bag<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> Bag<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
```
PartitionBag<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> PartitionBag<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> Bag<S> selectInstancesOf(java.lang.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>
  - groupBy
```
<V> BagMultimap<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> BagMultimap<V,T> groupByEach(Function<? super T,? extends java.lang.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>
  - zipWithIndex
```
SetIterable<Pair<T,java.lang.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)
  - forEachWithOccurrences
```
void forEachWithOccurrences(ObjectIntProcedure<? super T> procedure)
```
    For each distinct item, with the number of occurrences, execute the specified procedure.
  - occurrencesOf
```
int occurrencesOf(java.lang.Object item)
```
    The occurrences of a distinct item in the bag.
  - selectByOccurrences
```
Bag<T> selectByOccurrences(IntPredicate predicate)
```
    Returns all elements of the bag that have a number of occurrences that satisfy the predicate.
    
    Since:
    
    3.0
  - selectDuplicates
```
default Bag<T> selectDuplicates()
```
    Returns all elements of the bag that have more than one occurrence.
    
    Since:
    
    9.2
  - selectUnique
```
default SetIterable<T> selectUnique()
```
    Returns a set containing all elements of the bag that have exactly one occurrence.
    
    Since:
    
    9.2
  - topOccurrences
```
ListIterable<ObjectIntPair<T>> topOccurrences(int count)
```
    Returns the count most frequently occurring items. In the event of a tie, all of the items with the number of occurrences that match the occurrences of the last item will be returned.
    
    Since:
    
    6.0
  - bottomOccurrences
```
ListIterable<ObjectIntPair<T>> bottomOccurrences(int count)
```
    Returns the count least frequently occurring items. In the event of a tie, all of the items with the number of occurrences that match the occurrences of the last item will be returned.
    
    Since:
    
    6.0
  - sizeDistinct
```
int sizeDistinct()
```
    The size of the Bag when counting only distinct elements.
  - toMapOfItemToCount
```
MapIterable<T,java.lang.Integer> toMapOfItemToCount()
```
    Converts the Bag to a Map of the Item type to its count as an Integer.
  - toStringOfItemToCount
```
java.lang.String toStringOfItemToCount()
```
    Returns a string representation of this bag. The string representation consists of a list of element-count mappings.
```
 Assert.assertEquals("{1=1, 2=2, 3=3}", Bags.mutable.with(1, 2, 2, 3, 3, 3).toStringOfItemToCount());
 
```
    This string representation is similar to AbstractMap.toString(), not RichIterable.toString(), whereas the toString() implementation for a Bag is consistent with RichIterable.toString().
    Returns:
    
    a string representation of this bag
    
    Since:
    
    3.0
  - toImmutable
```
ImmutableBagIterable<T> toImmutable()
```
  - summarizeInt
```
default java.util.IntSummaryStatistics summarizeInt(IntFunction<? super T> function)
```
    Description copied from interface: RichIterable
    Returns the result of summarizing the value returned from applying the IntFunction to each element of the iterable.
```
 IntSummaryStatistics stats =
     Lists.mutable.with(1, 2, 3).summarizeInt(Integer::intValue);
 
```
    Specified by:
    
    summarizeInt in interface RichIterable<T>
    
    Since:
    
    8.0
  - summarizeFloat
```
default java.util.DoubleSummaryStatistics summarizeFloat(FloatFunction<? super T> function)
```
    Description copied from interface: RichIterable
    Returns the result of summarizing the value returned from applying the FloatFunction to each element of the iterable.
```
 DoubleSummaryStatistics stats =
     Lists.mutable.with(1, 2, 3).summarizeFloat(Integer::floatValue);
 
```
    Specified by:
    
    summarizeFloat in interface RichIterable<T>
    
    Since:
    
    8.0
  - summarizeLong
```
default java.util.LongSummaryStatistics summarizeLong(LongFunction<? super T> function)
```
    Description copied from interface: RichIterable
    Returns the result of summarizing the value returned from applying the LongFunction to each element of the iterable.
```
 LongSummaryStatistics stats =
     Lists.mutable.with(1, 2, 3).summarizeLong(Integer::longValue);
 
```
    Specified by:
    
    summarizeLong in interface RichIterable<T>
    
    Since:
    
    8.0
  - summarizeDouble
```
default java.util.DoubleSummaryStatistics summarizeDouble(DoubleFunction<? super T> function)
```
    Description copied from interface: RichIterable
    Returns the result of summarizing the value returned from applying the DoubleFunction to each element of the iterable.
```
 DoubleSummaryStatistics stats =
     Lists.mutable.with(1, 2, 3).summarizeDouble(Integer::doubleValue);
 
```
    Specified by:
    
    summarizeDouble in interface RichIterable<T>
    
    Since:
    
    8.0
  - reduceInPlace
```
default <R,A> R reduceInPlace(java.util.stream.Collector<? super T,A,R> collector)
```
    This method produces the equivalent result as Stream.collect(Collector).
    
    Specified by:
    
    reduceInPlace in interface RichIterable<T>
    
    Since:
    
    8.0
  - reduceInPlace
```
default <R> R reduceInPlace(java.util.function.Supplier<R> supplier,
                            java.util.function.BiConsumer<R,? super T> accumulator)
```
    This method produces the equivalent result as Stream.collect(Supplier, BiConsumer, BiConsumer).
    
    Specified by:
    
    reduceInPlace in interface RichIterable<T>
    
    Since:
    
    8.0
  - collectWithOccurrences
```
default <V,R extends java.util.Collection<V>> R collectWithOccurrences(ObjectIntToObjectFunction<? super T,? extends V> function,
                                                                       R target)
```
    Iterates over the unique elements and their occurrences and collects the results of applying the specified function into the target collection.
    
    Since:
    
    9.1.

Interface Bag<T>

Method Summary

Methods inherited from interface org.eclipse.collections.api.InternalIterable

Methods inherited from interface java.lang.Iterable

Methods inherited from interface org.eclipse.collections.api.RichIterable

Method Detail

equals

hashCode

tap

select

selectWith

reject

rejectWith

partition

partitionWith

selectInstancesOf

groupBy

groupByEach

zipWithIndex

forEachWithOccurrences

occurrencesOf

selectByOccurrences

selectDuplicates

selectUnique

topOccurrences

bottomOccurrences

sizeDistinct

toMapOfItemToCount

toStringOfItemToCount

toImmutable

summarizeInt

summarizeFloat

summarizeLong

summarizeDouble

reduceInPlace

reduceInPlace

collectWithOccurrences