Android
java.util
public abstract class

java.util.AbstractCollection<E>

java.lang.Object
java.util.AbstractCollection<E> Collection<E>

AbstractCollection is an abstract implementation of the Collection interface. This implementation does not support adding. A subclass must implement the abstract methods iterator() and size().

Known Direct Subclasses
Known Indirect Subclasses

Summary

Protected Constructors

            AbstractCollection()
Constructs a new instance of this AbstractCollection.

Public Methods

          boolean  add(E object)
If the specified element is not contained within this collection, and addition of this element succeeds, then true will be returned.
          boolean  addAll(Collection<? extends E> collection)
Adds the objects in the specified Collection to this Collection.
          void  clear()
Removes all the elements in this collection.
          boolean  contains(Object object)
Searches this Collection for the specified object.
          boolean  containsAll(Collection<?> collection)
Searches this Collection for all objects in the specified Collection.
          boolean  isEmpty()
Returns true if the collection has no element, otherwise false.
abstract          Iterator<E>  iterator()
Returns an Iterator on the elements of this Collection.
          boolean  remove(Object object)
Removes the first occurrence of the specified object from this Collection.
          boolean  removeAll(Collection<?> collection)
Removes all occurrences in this Collection of each object in the specified Collection.
          boolean  retainAll(Collection<?> collection)
Removes all objects from this Collection that are not contained in the specified Collection.
abstract          int  size()
Returns the number of elements in this Collection.
        <T>  T[]  toArray(T[] contents)
Returns an array containing all elements contained in this Collection.
          Object[]  toArray()
Returns a new array containing all elements contained in this Collection.
          String  toString()
Returns the string representation of this Collection.
Methods inherited from class java.lang.Object
Methods inherited from interface java.lang.Iterable
Methods inherited from interface java.util.Collection

Details

Protected Constructors

protected AbstractCollection()

Constructs a new instance of this AbstractCollection.

Public Methods

public boolean add(E object)

If the specified element is not contained within this collection, and addition of this element succeeds, then true will be returned. If the specified element is already contained within this collection, or duplication is not permitted, false will be returned. Different implementations may add specific limitations on this method to filter permitted elements. For example, in some implementation, null element may be denied, and NullPointerException will be thrown out. These limitations should be explicitly documented by specific collection implementation. Add operation is not supported in this implementation, and UnsupportedOperationException will always be thrown out.

Parameters

object the element to be added.

Returns

  • true if the collection is changed successfully after invoking this method. Otherwise, false.

Throws

UnsupportedOperationException if add operation is not supported by this class.
NullPointerException if null is used to invoke this method, and null is not permitted by this collection.
ClassCastException if the class type of the specified element is not compatible with the permitted class type.
IllegalArgumentException if limitations of this collection prevent the specified element from being added

public boolean addAll(Collection<? extends E> collection)

Adds the objects in the specified Collection to this Collection.

Parameters

collection the Collection of objects

Returns

  • true if this Collection is modified, false otherwise

Throws

UnsupportedOperationException when adding to this Collection is not supported
NullPointerException if null is used to invoke this method

public void clear()

Removes all the elements in this collection. This collection will be cleared up after this operation. The operation iterates over the collection, removes every element using Iterator.remove method. UnsupportedOperationException will be thrown out if the iterator returned by this collection does not implement the remove method and the collection is not zero length.

Throws

UnsupportedOperationException if this operation is not implemented.

public boolean contains(Object object)

Searches this Collection for the specified object.

Parameters

object the object to search for

Returns

  • true if object is an element of this Collection, false otherwise

public boolean containsAll(Collection<?> collection)

Searches this Collection for all objects in the specified Collection.

Parameters

collection the Collection of objects

Returns

  • true if all objects in the specified Collection are elements of this Collection, false otherwise

Throws

NullPointerException if null is used to invoke this method

public boolean isEmpty()

Returns true if the collection has no element, otherwise false.

Returns

  • true if the collection has no element.

public abstract Iterator<E> iterator()

Returns an Iterator on the elements of this Collection. A subclass must implement the abstract methods iterator() and size().

Returns

  • an Iterator on the elements of this Collection

See Also

public boolean remove(Object object)

Removes the first occurrence of the specified object from this Collection. This operation traverses over the collection, looking for the specified object. Once the object is found, the object will be removed from the collection using the iterator's remove method. This collection will throw an UnsupportedOperationException if the iterator returned does not implement remove method, and the specified object is in this collection.

Parameters

object the object to remove

Returns

  • true if this Collection is modified, false otherwise

Throws

UnsupportedOperationException when removing from this Collection is not supported

public boolean removeAll(Collection<?> collection)

Removes all occurrences in this Collection of each object in the specified Collection. This operation traverses over the collection itself, to verify whether each element is contained in the specified collection. The object will be removed from the collection itself using the iterator's remove method if it is contained in the specified collection. This collection will throw an UnsupportedOperationException if the iterator returned does not implement remove method, and the element in the specified collection is contained in this collection.

Parameters

collection the Collection of objects to remove

Returns

  • true if this Collection is modified, false otherwise

Throws

UnsupportedOperationException when removing from this Collection is not supported
NullPointerException if null is used to invoke this method

public boolean retainAll(Collection<?> collection)

Removes all objects from this Collection that are not contained in the specified Collection. This operation traverses over the collection itself, to verify whether any element is contained in the specified collection. The object will be removed from the collection itself using the iterator's remove method if it is not contained in the specified collection. This collection will throw an UnsupportedOperationException if the iterator returned does not implement remove method, and the collection itself does contain elements which do not exist in the specified collection.

Parameters

collection the Collection of objects to retain

Returns

  • true if this Collection is modified, false otherwise

Throws

UnsupportedOperationException when removing from this Collection is not supported
NullPointerException if null is used to invoke this method

public abstract int size()

Returns the number of elements in this Collection.

Returns

  • the number of elements in this Collection

public T[] toArray(T[] contents)

Returns an array containing all elements contained in this Collection. If the specified array is large enough to hold the elements, the specified array is used, otherwise an array of the same type is created. If the specified array is used and is larger than this Collection, the array element following the collection elements is set to null.

Parameters

contents the array

Returns

  • an array of the elements from this Collection

Throws

ArrayStoreException when the type of an element in this Collection cannot be stored in the type of the specified array
NullPointerException if null is used to invoke this method

public Object[] toArray()

Returns a new array containing all elements contained in this Collection. All the elements in the array will not be referenced by the collection. The elements in the returned array will be sorted to the same order as those returned by the iterator of this collection itself if the collection guarantees the order.

Returns

  • an array of the elements from this Collection

public String toString()

Returns the string representation of this Collection. The presentation has a specific format. It is enclosed by square brackets ("[]"). Elements are separated by ', ' (comma and space).

Returns

  • the string representation of this Collection
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