# Class ArrayStack<E>

java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractList<E>
java.util.ArrayList<E>
org.apache.commons.collections4.ArrayStack<E>

Type Parameters:
  `E` - the type of elements in this list

All Implemented Interfaces:
  `Serializable`, `Cloneable`, `Iterable<E>`, `Collection<E>`, `List<E>`, `RandomAccess`

@Deprecated public class ArrayStack<E> extends ArrayList<E>
Deprecated.
use `ArrayDeque` instead (available from Java 1.6)
An implementation of the `Stack` API that is based on an `ArrayList` instead of a `Vector`, so it is not synchronized to protect against multithreaded access. The implementation is therefore operates faster in environments where you do not need to worry about multiple thread contention.

The removal order of an `ArrayStack` is based on insertion order: The most recently added element is removed first. The iteration order is not the same as the removal order. The iterator returns elements from the bottom up.

Unlike `Stack`, `ArrayStack` accepts null entries.

Note: From version 4.0 onwards, this class does not implement the removed `Buffer` interface anymore.

Since:
  1.0
See Also:
  - `Stack`
  - Serialized Form

- ## Field Summary

  ### Fields inherited from class java.util.AbstractList

  `modCount`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ArrayStack()`
  Deprecated.
  Constructs a new empty `ArrayStack`.
  `ArrayStack(int initialSize)`
  Deprecated.
  Constructs a new empty `ArrayStack` with an initial size.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `empty()`
  Deprecated.
  Return `true` if this stack is currently empty.
  `E`
  `peek()`
  Deprecated.
  Returns the top item off of this stack without removing it.
  `E`
  `peek(int n)`
  Deprecated.
  Returns the n'th item down (zero-relative) from the top of this stack without removing it.
  `E`
  `pop()`
  Deprecated.
  Pops the top item off of this stack and return it.
  `E`
  `push(E item)`
  Deprecated.
  Pushes a new item onto the top of this stack.
  `int`
  `search(Object object)`
  Deprecated.
  Returns the one-based position of the distance from the top that the specified object exists on this stack, where the top-most element is considered to be at distance `1`.

  ### Methods inherited from class java.util.ArrayList

  `add, add, addAll, addAll, clear, clone, 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.Collection

  `parallelStream, stream`

  ### Methods inherited from interface java.util.List

  `containsAll, equals, hashCode`

- ## Constructor Details

  - ### ArrayStack

    public ArrayStack()
    Deprecated.
    Constructs a new empty `ArrayStack`. The initial size is controlled by `ArrayList` and is currently 10.

  - ### ArrayStack

    public ArrayStack(int initialSize)
    Deprecated.
    Constructs a new empty `ArrayStack` with an initial size.
    Parameters:
      `initialSize` - the initial size to use
    Throws:
      `IllegalArgumentException` - if the specified initial size is negative

- ## Method Details

  - ### empty

    public boolean empty()
    Deprecated.
    Return `true` if this stack is currently empty.

    This method exists for compatibility with `Stack`. New users of this class should use `isEmpty` instead.

    Returns:
      true if the stack is currently empty

  - ### peek

    public E peek() throws EmptyStackException
    Deprecated.
    Returns the top item off of this stack without removing it.
    Returns:
      the top item on the stack
    Throws:
      `EmptyStackException` - if the stack is empty

  - ### peek

    public E peek(int n) throws EmptyStackException
    Deprecated.
    Returns the n'th item down (zero-relative) from the top of this stack without removing it.
    Parameters:
      `n` - the number of items down to go
    Returns:
      the n'th item on the stack, zero relative
    Throws:
      `EmptyStackException` - if there are not enough items on the stack to satisfy this request

  - ### pop

    public E pop() throws EmptyStackException
    Deprecated.
    Pops the top item off of this stack and return it.
    Returns:
      the top item on the stack
    Throws:
      `EmptyStackException` - if the stack is empty

  - ### push

    public E push(E item)
    Deprecated.
    Pushes a new item onto the top of this stack. The pushed item is also returned. This is equivalent to calling `add`.
    Parameters:
      `item` - the item to be added
    Returns:
      the item just pushed

  - ### search

    public int search(Object object)
    Deprecated.
    Returns the one-based position of the distance from the top that the specified object exists on this stack, where the top-most element is considered to be at distance `1`. If the object is not present on the stack, return `-1` instead. The `equals()` method is used to compare to the items in this stack.
    Parameters:
      `object` - the object to be searched for
    Returns:
      the 1-based depth into the stack of the object, or -1 if not found