public class

ArrayStack

extends ArrayList
implements Buffer
java.lang.Object
   ↳ java.util.AbstractCollection
     ↳ java.util.AbstractList
       ↳ java.util.ArrayList
         ↳ org.apache.commons.collections.ArrayStack

Class Overview

An implementation of the java.util.Stack API that is based on an ArrayList instead of a Vector, so it is not synchronized to protect against multi-threaded 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, whereas the remove() method removes them from the top down.

Unlike Stack, ArrayStack accepts null entries.

Note: this class should be bytecode-identical to the version in commons collections. This is required to allow backwards compability with both previous versions of BeanUtils and also allow coexistance with both collections 2.1 and 3.0.

See Also
  • java.util.Stack

Summary

[Expand]
Inherited Fields
From class java.util.AbstractList
Public Constructors
ArrayStack()
Constructs a new empty ArrayStack.
ArrayStack(int initialSize)
Constructs a new empty ArrayStack with an initial size.
Public Methods
boolean empty()
Return true if this stack is currently empty.
Object get()
Returns the element on the top of the stack.
Object peek(int n)
Returns the n'th item down (zero-relative) from the top of this stack without removing it.
Object peek()
Returns the top item off of this stack without removing it.
Object pop()
Pops the top item off of this stack and return it.
Object push(Object item)
Pushes a new item onto the top of this stack.
Object remove()
Removes the element on the top of the stack.
int search(Object object)
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.
[Expand]
Inherited Methods
From class java.util.ArrayList
From class java.util.AbstractList
From class java.util.AbstractCollection
From class java.lang.Object
From interface java.lang.Iterable
From interface java.util.Collection
From interface java.util.List
From interface org.apache.commons.collections.Buffer

Public Constructors

public ArrayStack ()

Also: Collections

Constructs a new empty ArrayStack. The initial size is controlled by ArrayList and is currently 10.

public ArrayStack (int initialSize)

Also: Collections

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

Public Methods

public boolean empty ()

Also: Collections

Return true if this stack is currently empty.

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

Returns
  • true if the stack is currently empty

public Object get ()

Also: Collections

Returns the element on the top of the stack.

Returns
  • the element on the top of the stack
Throws
BufferUnderflowException if the stack is empty

public Object peek (int n)

Also: Collections

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

public Object peek ()

Also: Collections

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

public Object pop ()

Also: Collections

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

public Object push (Object item)

Also: Collections

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

public Object remove ()

Also: Collections

Removes the element on the top of the stack.

Returns
  • the removed element
Throws
BufferUnderflowException if the stack is empty

public int search (Object object)

Also: Collections

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