protected AbstractCollection()
Sole constructor. (For invocation by subclass constructors, typically implicit.)
public abstract Iterator<E> iterator()
Returns an iterator over the elements contained in this collection.
public boolean isEmpty()
Returns true if this collection contains no elements.
isEmpty in interface Collection<E>
size() == 0.
true if this collection contains no elements
public boolean contains(Object o)
Returns true if this collection contains the specified element. More formally, returns true if and only if this collection contains at least one element e such that Objects.equals(o, e).
contains in interface Collection<E>
o - element whose presence in this collection is to be tested
true if this collection contains the specified element
ClassCastException - if the type of the specified element is incompatible with this collection (optional)
NullPointerException - if the specified element is null and this collection does not permit null elements (optional)
public Object[] toArray()
Returns an array containing all of the elements in this collection. If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order. The returned array's
runtime component typeis
Object
.
The returned array will be "safe" in that no references to it are maintained by this collection. (In other words, this method must allocate a new array even if this collection is backed by an array). The caller is thus free to modify the returned array.
toArray in interface Collection<E>
0. The length of the returned array is equal to the number of elements returned by the iterator, even if the size of this collection changes during iteration, as might happen if the collection permits concurrent modification during iteration. The size method is called only as an optimization hint; the correct result is returned even if the iterator returns a different number of elements.
This method is equivalent to:
List<E> list = new ArrayList<E>(size());
for (E e : this)
list.add(e);
return list.toArray();
Object, containing all of the elements in this collection
public <T> T[] toArray(T[] a)
Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. If the collection fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this collection.
If this collection fits in the specified array with room to spare (i.e., the array has more elements than this collection), the element in the array immediately following the end of the collection is set to null. (This is useful in determining the length of this collection only if the caller knows that this collection does not contain any null elements.)
If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.
toArray in interface Collection<E>
0. If the number of elements returned by the iterator is too large to fit into the specified array, then the elements are returned in a newly allocated array with length equal to the number of elements returned by the iterator, even if the size of this collection changes during iteration, as might happen if the collection permits concurrent modification during iteration. The size method is called only as an optimization hint; the correct result is returned even if the iterator returns a different number of elements.
This method is equivalent to:
List<E> list = new ArrayList<E>(size());
for (E e : this)
list.add(e);
return list.toArray(a);
T - the component type of the array to contain the collection
a - the array into which the elements of this collection are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
ArrayStoreException - if the runtime type of any element in this collection is not assignable to the runtime component type of the specified array
NullPointerException - if the specified array is null
public boolean add(E e)
Ensures that this collection contains the specified element (optional operation). Returns
true
if this collection changed as a result of the call. (Returns
false
if this collection does not permit duplicates and already contains the specified element.)
Collections that support this operation may place limitations on what elements may be added to this collection. In particular, some collections will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. Collection classes should clearly specify in their documentation any restrictions on what elements may be added.
If a collection refuses to add a particular element for any reason other than that it already contains the element, it must throw an exception (rather than returning false). This preserves the invariant that a collection always contains the specified element after this call returns.
add in interface Collection<E>
UnsupportedOperationException.
e - element whose presence in this collection is to be ensured
true if this collection changed as a result of the call
UnsupportedOperationException - if the add operation is not supported by this collection
ClassCastException - if the class of the specified element prevents it from being added to this collection
NullPointerException - if the specified element is null and this collection does not permit null elements
IllegalArgumentException - if some property of the element prevents it from being added to this collection
IllegalStateException - if the element cannot be added at this time due to insertion restrictions
public boolean remove(Object o)
Removes a single instance of the specified element from this collection, if it is present (optional operation). More formally, removes an element e such that Objects.equals(o, e), if this collection contains one or more such elements. Returns true if this collection contained the specified element (or equivalently, if this collection changed as a result of the call).
remove in interface Collection<E>
Note that this implementation throws an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method and this collection contains the specified object.
o - element to be removed from this collection, if present
true if an element was removed as a result of this call
UnsupportedOperationException - if the remove operation is not supported by this collection
ClassCastException - if the type of the specified element is incompatible with this collection (optional)
NullPointerException - if the specified element is null and this collection does not permit null elements (optional)
public boolean containsAll(Collection<?> c)
Returns true if this collection contains all of the elements in the specified collection.
containsAll in interface Collection<E>
true is returned, otherwise false.
c - collection to be checked for containment in this collection
true if this collection contains all of the elements in the specified collection
ClassCastException - if the types of one or more elements in the specified collection are incompatible with this collection (optional)
NullPointerException - if the specified collection contains one or more null elements and this collection does not permit null elements (optional), or if the specified collection is null.
contains(Object)
public boolean addAll(Collection<? extends E> c)
Adds all of the elements in the specified collection to this collection (optional operation). The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (This implies that the behavior of this call is undefined if the specified collection is this collection, and this collection is nonempty.)
addAll in interface Collection<E>
Note that this implementation will throw an UnsupportedOperationException unless add is overridden (assuming the specified collection is non-empty).
c - collection containing elements to be added to this collection
true if this collection changed as a result of the call
UnsupportedOperationException - if the addAll operation is not supported by this collection
ClassCastException - if the class of an element of the specified collection prevents it from being added to this collection
NullPointerException - if the specified collection contains a null element and this collection does not permit null elements, or if the specified collection is null
IllegalArgumentException - if some property of an element of the specified collection prevents it from being added to this collection
IllegalStateException - if not all the elements can be added at this time due to insertion restrictions
add(Object)
public boolean removeAll(Collection<?> c)
Removes all of this collection's elements that are also contained in the specified collection (optional operation). After this call returns, this collection will contain no elements in common with the specified collection.
removeAll in interface Collection<E>
remove method.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by the iterator method does not implement the remove method and this collection contains one or more elements in common with the specified collection.
c - collection containing elements to be removed from this collection
true if this collection changed as a result of the call
UnsupportedOperationException - if the removeAll method is not supported by this collection
ClassCastException - if the types of one or more elements in this collection are incompatible with the specified collection (optional)
NullPointerException - if this collection contains one or more null elements and the specified collection does not support null elements (optional), or if the specified collection is null
remove(Object), contains(Object)
public boolean retainAll(Collection<?> c)
Retains only the elements in this collection that are contained in the specified collection (optional operation). In other words, removes from this collection all of its elements that are not contained in the specified collection.
retainAll in interface Collection<E>
remove method.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by the iterator method does not implement the remove method and this collection contains one or more elements not present in the specified collection.
c - collection containing elements to be retained in this collection
true if this collection changed as a result of the call
UnsupportedOperationException - if the retainAll operation is not supported by this collection
ClassCastException - if the types of one or more elements in this collection are incompatible with the specified collection (optional)
NullPointerException - if this collection contains one or more null elements and the specified collection does not permit null elements (optional), or if the specified collection is null
remove(Object), contains(Object)
public void clear()
Removes all of the elements from this collection (optional operation). The collection will be empty after this method returns.
clear in interface Collection<E>
Iterator.remove operation. Most implementations will probably choose to override this method for efficiency.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method and this collection is non-empty.
UnsupportedOperationException - if the clear operation is not supported by this collection
public String toString()
Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(comma and space). Elements are converted to strings as by
String.valueOf(Object)
.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4