AbstractMapBag (Apache Commons Collections 4.4 API)

java.lang.Object
- org.apache.commons.collections4.bag.AbstractMapBag<E>

Type Parameters:

E - the type of elements in this bag

All Implemented Interfaces:

Iterable<E>, Collection<E>, Bag<E>

Direct Known Subclasses:

HashBag, TreeBag
```
public abstract class AbstractMapBag<E>
extends Object
implements Bag<E>
```
Abstract implementation of the Bag interface to simplify the creation of subclass implementations.
Subclasses specify a Map implementation to use as the internal storage. The map will be used to map bag elements to a number; the number represents the number of occurrences of that element in the bag.

Since:

3.0 (previously DefaultMapBag v2.0)

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

protected static class AbstractMapBag.MutableInteger
Mutable integer class for storing the data.

Nested Classes
Modifier and Type	Class and Description
`protected static class`	`AbstractMapBag.MutableInteger` Mutable integer class for storing the data.

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`AbstractMapBag()` Constructor needed for subclass serialisation.
`protected`	`AbstractMapBag(Map<E,AbstractMapBag.MutableInteger> map)` Constructor that assigns the specified Map as the backing store.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`add(E object)` Adds a new element to the bag, incrementing its count in the underlying map.
`boolean`	`add(E object, int nCopies)` Adds a new element to the bag, incrementing its count in the map.
`boolean`	`addAll(Collection<? extends E> coll)` Invokes `add(Object)` for each element in the given collection.
`void`	`clear()` Clears the bag by clearing the underlying map.
`boolean`	`contains(Object object)` Determines if the bag contains the given element by checking if the underlying map contains the element as a key.
`boolean`	`containsAll(Collection<?> coll)` Determines if the bag contains the given elements.
`protected void`	`doReadObject(Map<E,AbstractMapBag.MutableInteger> map, ObjectInputStream in)` Read the map in using a custom routine.
`protected void`	`doWriteObject(ObjectOutputStream out)` Write the map out using a custom routine.
`boolean`	`equals(Object object)` Compares this Bag to another.
`int`	`getCount(Object object)` Returns the number of occurrence of the given element in this bag by looking up its count in the underlying map.
`protected Map<E,AbstractMapBag.MutableInteger>`	`getMap()` Utility method for implementations to access the map that backs this bag.
`int`	`hashCode()` Gets a hash code for the Bag compatible with the definition of equals.
`boolean`	`isEmpty()` Returns true if the underlying map is empty.
`Iterator<E>`	`iterator()` Gets an iterator over the bag elements.
`boolean`	`remove(Object object)` Removes all copies of the specified object from the bag.
`boolean`	`remove(Object object, int nCopies)` Removes a specified number of copies of an object from the bag.
`boolean`	`removeAll(Collection<?> coll)` Removes objects from the bag according to their count in the specified collection.
`boolean`	`retainAll(Collection<?> coll)` Remove any members of the bag that are not in the given bag, respecting cardinality.
`int`	`size()` Returns the number of elements in this bag.
`Object[]`	`toArray()` Returns an array of all of this bag's elements.
`<T> T[]`	`toArray(T[] array)` Returns an array of all of this bag's elements.
`String`	`toString()` Implement a toString() method suitable for debugging.
`Set<E>`	`uniqueSet()` Returns an unmodifiable view of the underlying map's key set.

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

Methods inherited from interface java.util.Collection
parallelStream, removeIf, spliterator, stream

Methods inherited from interface java.lang.Iterable
forEach

- Constructor Detail
  - AbstractMapBag
```
protected AbstractMapBag()
```
    Constructor needed for subclass serialisation.
  - AbstractMapBag
```
protected AbstractMapBag(Map<E,AbstractMapBag.MutableInteger> map)
```
    Constructor that assigns the specified Map as the backing store. The map must be empty and non-null.
    
    Parameters:
    
    map - the map to assign
- Method Detail
  - getMap
```
protected Map<E,AbstractMapBag.MutableInteger> getMap()
```
    Utility method for implementations to access the map that backs this bag. Not intended for interactive use outside of subclasses.
    
    Returns:
    
    the map being used by the Bag
  - size
```
public int size()
```
    Returns the number of elements in this bag.
    
    Specified by:
    
    size in interface Collection<E>
    
    Specified by:
    
    size in interface Bag<E>
    
    Returns:
    
    current size of the bag
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if the underlying map is empty.
    
    Specified by:
    
    isEmpty in interface Collection<E>
    
    Returns:
    
    true if bag is empty
  - getCount
```
public int getCount(Object object)
```
    Returns the number of occurrence of the given element in this bag by looking up its count in the underlying map.
    
    Specified by:
    
    getCount in interface Bag<E>
    
    Parameters:
    
    object - the object to search for
    
    Returns:
    
    the number of occurrences of the object, zero if not found
  - contains
```
public boolean contains(Object object)
```
    Determines if the bag contains the given element by checking if the underlying map contains the element as a key.
    
    Specified by:
    
    contains in interface Collection<E>
    
    Parameters:
    
    object - the object to search for
    
    Returns:
    
    true if the bag contains the given element
  - containsAll
```
public boolean containsAll(Collection<?> coll)
```
    Determines if the bag contains the given elements.
    
    Specified by:
    
    containsAll in interface Collection<E>
    
    Specified by:
    
    containsAll in interface Bag<E>
    
    Parameters:
    
    coll - the collection to check against
    
    Returns:
    
    true if the Bag contains all the collection
  - iterator
```
public Iterator<E> iterator()
```
    Gets an iterator over the bag elements. Elements present in the Bag more than once will be returned repeatedly.
    
    Specified by:
    
    iterator in interface Iterable<E>
    
    Specified by:
    
    iterator in interface Collection<E>
    
    Specified by:
    
    iterator in interface Bag<E>
    
    Returns:
    
    the iterator
  - add
```
public boolean add(E object)
```
    Adds a new element to the bag, incrementing its count in the underlying map.
    
    Specified by:
    
    add in interface Collection<E>
    
    Specified by:
    
    add in interface Bag<E>
    
    Parameters:
    
    object - the object to add
    
    Returns:
    
    true if the object was not already in the uniqueSet
  - add
```
public boolean add(E object,
                   int nCopies)
```
    Adds a new element to the bag, incrementing its count in the map.
    
    Specified by:
    
    add in interface Bag<E>
    
    Parameters:
    
    object - the object to search for
    
    nCopies - the number of copies to add
    
    Returns:
    
    true if the object was not already in the uniqueSet
  - addAll
```
public boolean addAll(Collection<? extends E> coll)
```
    Invokes add(Object) for each element in the given collection.
    
    Specified by:
    
    addAll in interface Collection<E>
    
    Parameters:
    
    coll - the collection to add
    
    Returns:
    
    true if this call changed the bag
  - clear
```
public void clear()
```
    Clears the bag by clearing the underlying map.
    
    Specified by:
    
    clear in interface Collection<E>
  - remove
```
public boolean remove(Object object)
```
    Removes all copies of the specified object from the bag.
    
    Specified by:
    
    remove in interface Collection<E>
    
    Specified by:
    
    remove in interface Bag<E>
    
    Parameters:
    
    object - the object to remove
    
    Returns:
    
    true if the bag changed
  - remove
```
public boolean remove(Object object,
                      int nCopies)
```
    Removes a specified number of copies of an object from the bag.
    
    Specified by:
    
    remove in interface Bag<E>
    
    Parameters:
    
    object - the object to remove
    
    nCopies - the number of copies to remove
    
    Returns:
    
    true if the bag changed
  - removeAll
```
public boolean removeAll(Collection<?> coll)
```
    Removes objects from the bag according to their count in the specified collection.
    
    Specified by:
    
    removeAll in interface Collection<E>
    
    Specified by:
    
    removeAll in interface Bag<E>
    
    Parameters:
    
    coll - the collection to use
    
    Returns:
    
    true if the bag changed
  - retainAll
```
public boolean retainAll(Collection<?> coll)
```
    Remove any members of the bag that are not in the given bag, respecting cardinality.
    
    Specified by:
    
    retainAll in interface Collection<E>
    
    Specified by:
    
    retainAll in interface Bag<E>
    
    Parameters:
    
    coll - the collection to retain
    
    Returns:
    
    true if this call changed the collection
  - toArray
```
public Object[] toArray()
```
    Returns an array of all of this bag's elements.
    
    Specified by:
    
    toArray in interface Collection<E>
    
    Returns:
    
    an array of all of this bag's elements
  - toArray
```
public <T> T[] toArray(T[] array)
```
    Returns an array of all of this bag's elements. If the input array has more elements than are in the bag, trailing elements will be set to null.
    
    Specified by:
    
    toArray in interface Collection<E>
    
    Type Parameters:
    
    T - the type of the array elements
    
    Parameters:
    
    array - the array to populate
    
    Returns:
    
    an array of all of this bag's elements
    
    Throws:
    
    ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of the elements in this list
    
    NullPointerException - if the specified array is null
  - uniqueSet
```
public Set<E> uniqueSet()
```
    Returns an unmodifiable view of the underlying map's key set.
    
    Specified by:
    
    uniqueSet in interface Bag<E>
    
    Returns:
    
    the set of unique elements in this bag
  - doWriteObject
```
protected void doWriteObject(ObjectOutputStream out)
                      throws IOException
```
    Write the map out using a custom routine.
    
    Parameters:
    
    out - the output stream
    
    Throws:
    
    IOException - any of the usual I/O related exceptions
  - doReadObject
```
protected void doReadObject(Map<E,AbstractMapBag.MutableInteger> map,
                            ObjectInputStream in)
                     throws IOException,
                            ClassNotFoundException
```
    Read the map in using a custom routine.
    
    Parameters:
    
    map - the map to use
    
    in - the input stream
    
    Throws:
    
    IOException - any of the usual I/O related exceptions
    
    ClassNotFoundException - if the stream contains an object which class can not be loaded
    
    ClassCastException - if the stream does not contain the correct objects
  - equals
```
public boolean equals(Object object)
```
    Compares this Bag to another. This Bag equals another Bag if it contains the same number of occurrences of the same elements.
    
    Specified by:
    
    equals in interface Collection<E>
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    
    object - the Bag to compare to
    
    Returns:
    
    true if equal
  - hashCode
```
public int hashCode()
```
    Gets a hash code for the Bag compatible with the definition of equals. The hash code is defined as the sum total of a hash code for each element. The per element hash code is defined as (e==null ? 0 : e.hashCode()) ^ noOccurances). This hash code is compatible with the Set interface.
    
    Specified by:
    
    hashCode in interface Collection<E>
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    
    the hash code of the Bag
  - toString
```
public String toString()
```
    Implement a toString() method suitable for debugging.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    a debugging toString

Class AbstractMapBag<E>

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Collection

Methods inherited from interface java.lang.Iterable

Constructor Detail

AbstractMapBag

AbstractMapBag

Method Detail

getMap

size

isEmpty

getCount

contains

containsAll

iterator

add

add

addAll

clear

remove

remove

removeAll

retainAll

toArray

toArray

uniqueSet

doWriteObject

doReadObject

equals

hashCode

toString