public class IlvUnsynchronizedStack<E> extends ArrayList<E> implements Queue<E>
Queue interface and allow the list to be treated as a
stack. Because it is based on ArrayList, this class is unsynchronized.
Therefore, it gives better performance than the standard JDK Stack class.
The offer(E) method is identical to ArrayList.add(Object) in that it
pushes an item onto the stack and always returns true. A
push method is also provided that mimics the JDK's
Stack class. Although ArrayList allows insertion of
null items, you should avoid inserting them into an
IlvUnsynchronizedStack because null is also used as a special return
value by the poll() method to indicate that the stack contains no elements.
The poll(), remove(), and pop() methods remove and
return the item from the top of the stack. The remove and pop
methods differ only in the type of exceptions that they throw when the stack is empty.
The poll method differs from the other two in that it returns
null when the stack is empty. The element() and peek()
methods return, but do not remove, the item at the top of the stack.
modCount| Constructor and Description |
|---|
IlvUnsynchronizedStack()
Constructs an empty stack with an initial capacity of ten.
|
IlvUnsynchronizedStack(int initialCapacity)
Constructs an empty stack with the specified initial capacity.
|
| Modifier and Type | Method and Description |
|---|---|
Object |
clone()
Returns a shallow copy of this IlvUnsynchronizedStack instance.
|
E |
element()
Returns the object at the top of the stack without removing it from the stack.
|
boolean |
empty()
Returns whether this stack is empty.
|
boolean |
offer(E item)
Pushes an item onto the top of the stack by adding it to the end of the list.
|
E |
peek()
Returns the object at the top of the stack without removing it from the stack.
|
E |
poll()
Removes the object at the top of the stack and returns that item as the value of
this method.
|
E |
pop()
Removes the object at the top of the stack and returns that item as the value of
this method.
|
E |
push(E item)
Pushes an item onto the top of the stack.
|
E |
remove()
Removes the object at the top of the stack and returns that item as the value of
this method.
|
add, add, addAll, addAll, clear, contains, ensureCapacity, forEach, get, indexOf, isEmpty, iterator, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, removeIf, removeRange, replaceAll, retainAll, set, size, sort, spliterator, subList, toArray, toArray, trimToSizeequals, hashCodecontainsAll, toStringfinalize, getClass, notify, notifyAll, wait, wait, waitaddAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, remove, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArraycontainsAll, equals, hashCodepublic IlvUnsynchronizedStack(int initialCapacity)
initialCapacity - The initial capacity of the stack.IllegalArgumentException - if the specified initial capacity
is negativepublic IlvUnsynchronizedStack()
public Object clone()
public boolean offer(E item)
Although this class does not prohibit the insertion of null items,
you should avoid inserting them because because null is also used as a
special return value by the poll() method to indicate that the stack contains
no elements.
offer in interface Queue<E>item - The item to push onto the stack.push(E),
ArrayList.add(Object)public E poll()
public E remove()
poll() method in that it throws an
exception instead of returning null if the stack is empty. This method
differs from the pop() method in that it throws a NoSuchElementException
instead of an EmptyStackException if the stack is empty.public E peek()
element() and java.util.Stack.peek()
methods in that it returns null instead of throwing an exception if the
stack is empty.public E element()
peek() method in that it throws an exception instead of
returning null if the stack is empty.element in interface Queue<E>NoSuchElementException - if the stack is empty.peek()public E push(E item)
Although this class does not prohibit the insertion of null items,
you should avoid inserting them because because null is also used as a
special return value by the poll() method to indicate that the stack contains
no elements.
item - The item to be pushed onto this stack.item argument.offer(E),
ArrayList.add(Object)public E pop()
poll() method in that it throws an
exception instead of returning null if the stack is empty. This method
differs from the remove() method in that it throws an EmptyStackException
instead of a NoSuchElementException if the stack is empty.public boolean empty()
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