Apache Commons Collections 4.4 · org.apache.commons.collections4.ArrayStack

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.

Unlike Stack, ArrayStack accepts null entries.

Note

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

Modifier and Type	Field and Description
private static final long	serialVersionUID Hides java.util.ArrayList.serialVersionUID. Ensure serialization compatibility

Constructor Summary

Access	Constructor and Description
public	ArrayStack() Constructs a new empty `ArrayStack`.
public	ArrayStack(final int the initial size to use initialSize) Constructs a new empty `ArrayStack` with an initial size.

Method Summary

Modifier and Type	Method and Description
public boolean	Returns: true if the stack is currently empty empty() Return `true` if this stack is currently empty.
public E	Returns: the top item on the stack peek() Returns the top item off of this stack without removing it.
public E	Returns: the n'th item on the stack, zero relative peek(final int the number of items down to go n) Returns the n'th item down (zero-relative) from the top of this stack without removing it.
public E	Returns: the top item on the stack pop() Pops the top item off of this stack and return it.
public E	Returns: the item just pushed push(final E the item to be added item) Pushes a new item onto the top of this stack.
public int	Returns: the 1-based depth into the stack of the object, or -1 if not found search(final Object the object to be searched for 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`.

Field Detail

serialVersionUID	back to summary
private static final long serialVersionUID Hides java.util.ArrayList.serialVersionUID. Ensure serialization compatibility

serialVersionUID

back to summary

private static final long serialVersionUID

Hides java.util.ArrayList.serialVersionUID.

Ensure serialization compatibility

Constructor Detail

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

ArrayStack back to summary

ArrayStack	back to summary
public ArrayStack(final int initialSize) Constructs a new empty `ArrayStack` with an initial size. Parameters initialSize:int the initial size to use Exceptions IllegalArgumentException: if the specified initial size is negative

public ArrayStack(final int initialSize)

Constructs a new empty ArrayStack with an initial size.

Parameters

initialSize:int: the initial size to use

Exceptions

IllegalArgumentException:: if the specified initial size is negative

Method Detail

empty back to summary

empty	back to summary
public boolean empty() 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:boolean true if the stack is currently empty

public boolean empty()

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:boolean: true if the stack is currently empty

peek	back to summary
public E peek() throws EmptyStackException Returns the top item off of this stack without removing it. Returns:E the top item on the stack Exceptions EmptyStackException: if the stack is empty

peek

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public E peek() throws EmptyStackException

Returns the top item off of this stack without removing it.

Returns:E

the top item on the stack

Exceptions

EmptyStackException:: if the stack is empty

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

peek

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public E peek(final int n) throws EmptyStackException

Returns the n'th item down (zero-relative) from the top of this stack without removing it.

Parameters

n:int: the number of items down to go

Returns:E

the n'th item on the stack, zero relative

Exceptions

EmptyStackException:: if there are not enough items on the stack to satisfy this request

pop	back to summary
public E pop() throws EmptyStackException Pops the top item off of this stack and return it. Returns:E the top item on the stack Exceptions EmptyStackException: if the stack is empty

pop

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public E pop() throws EmptyStackException

Pops the top item off of this stack and return it.

Returns:E

the top item on the stack

Exceptions

EmptyStackException:: if the stack is empty

push back to summary

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

public E push(final E item)

Pushes a new item onto the top of this stack. The pushed item is also returned. This is equivalent to calling add.

Parameters

item:E: the item to be added

Returns:E

the item just pushed

search back to summary

search	back to summary
public int search(final 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`. 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:Object the object to be searched for Returns:int the 1-based depth into the stack of the object, or -1 if not found

public int search(final 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. 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:Object: the object to be searched for

Returns:int

the 1-based depth into the stack of the object, or -1 if not found

public Class ArrayStack<E>

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail