ilog.views.util.collections

Class IlvUnsynchronizedStack<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

java.util.ArrayList<E>

ilog.views.util.collections.IlvUnsynchronizedStack<E>

All Implemented Interfaces:

Serializable, Cloneable, Iterable<E>, Collection<E>, List<E>, Queue<E>, RandomAccess

public class IlvUnsynchronizedStack<E>
extends ArrayList<E>
implements Queue<E>

This class represents a last-in-first-out (LIFO) stack of objects. It extends class ArrayList with operations that match the semantics of the JDK 1.5 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.

Since:

JViews 7.5

See Also:

Serialized Form

Field Summary

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Constructors

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.

Method Summary

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.

Methods inherited from class java.util.ArrayList

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, trimToSize

Methods inherited from class java.util.AbstractList

equals, hashCode

Methods inherited from class java.util.AbstractCollection

containsAll, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Queue

add

Methods inherited from interface java.util.Collection

addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, remove, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.List

containsAll, equals, hashCode

Constructor Detail

IlvUnsynchronizedStack

public IlvUnsynchronizedStack(int initialCapacity)

Constructs an empty stack with the specified initial capacity.

Parameters:

initialCapacity - The initial capacity of the stack.

Throws:

IllegalArgumentException - if the specified initial capacity is negative

IlvUnsynchronizedStack

public IlvUnsynchronizedStack()

Constructs an empty stack with an initial capacity of ten.

Method Detail

clone

public Object clone()

Returns a shallow copy of this IlvUnsynchronizedStack instance. (The elements themselves are not copied.)

Overrides:

clone in class ArrayList<E>

Returns:

A clone of this IlvUnsynchronizedStack instance

Since:

JViews 8.5

offer

public boolean offer(E item)

Pushes an item onto the top of the stack by adding it to the end of the list.

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.

Specified by:

offer in interface Queue<E>

Parameters:

item - The item to push onto the stack.

Returns:

true, indicating that an item can always be pushed onto the stack.

See Also:

push(E), ArrayList.add(Object)

poll

public E poll()

Removes the object at the top of the stack and returns that item as the value of this method.

Specified by:

poll in interface Queue<E>

Returns:

The object at the top of the stack, or null if the stack is empty.

See Also:

remove(), pop()

remove

public E remove()

Removes the object at the top of the stack and returns that item as the value of this method. This method differs from the 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.

Specified by:

remove in interface Queue<E>

Returns:

The object at the top of the stack.

Throws:

NoSuchElementException - if the stack is empty.

See Also:

poll(), pop()

peek

public E peek()

Returns the object at the top of the stack without removing it from the stack. This method differs from the element() and java.util.Stack.peek() methods in that it returns null instead of throwing an exception if the stack is empty.

Specified by:

peek in interface Queue<E>

Returns:

The object at the top of the stack, or null if the stack is empty.

See Also:

element()

element

public E element()

Returns the object at the top of the stack without removing it from the stack. This method differs from the peek() method in that it throws an exception instead of returning null if the stack is empty.

Specified by:

element in interface Queue<E>

Returns:

The object at the top of the stack.

Throws:

NoSuchElementException - if the stack is empty.

See Also:

peek()

push

public E push(E item)

Pushes an item onto the top of the stack.

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.

Parameters:

item - The item to be pushed onto this stack.

Returns:

The item argument.

See Also:

offer(E), ArrayList.add(Object)

pop

public E pop()

Removes the object at the top of the stack and returns that item as the value of this method. This method differs from the 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.

Returns:

The object at the top of the stack.

Throws:

EmptyStackException - if this stack is empty.

See Also:

poll(), pop()

empty

public boolean empty()

Returns whether this stack is empty.

Returns:

Whether this stack contains no items.