java.util
Class Stack<E>

java.lang.Object
  |
  +--java.util.AbstractCollection<E>
        |
        +--java.util.AbstractList<A>
              |
              +--java.util.Vector<E>
                    |
                    +--java.util.Stack<E>

All Implemented Interfaces:

java.lang.Cloneable, Collection<E>, List<E>, java.util.RandomAccess, java.io.Serializable

public class Stack<E>

extends Vector<E>

The Stack class represents a last-in-first-out (LIFO) stack of objects. It extends class Vector with five operations that allow a vector to be treated as a stack. The usual push and pop operations are provided, as well as a method to peek at the top item on the stack, a method to test for whether the stack is empty, and a method to search the stack for an item and discover how far it is from the top.

When a stack is first created, it contains no items.

Since:

JDK1.0

See Also:

Serialized Form

Fields inherited from class java.util.Vector<E>

capacityIncrement, elementCount, elementData

Fields inherited from class java.util.AbstractList<A>

modCount

Constructor Summary

Stack()
Creates an empty Stack.

Method Summary

boolean	empty() Tests if this stack is empty.
E	peek() Looks at the object at the top of this stack without removing it from the stack.
E	pop() Removes the object at the top of this stack and returns that object as the value of this function.
E	push(E item) Pushes an item onto the top of this stack.
int	search(java.lang.Object o) Returns the 1-based position where an object is on this stack.

Methods inherited from class java.util.Vector<E>

<T>containsAll, <T>removeAll, <T>retainAll, <T>toArray, add, add, addAll, addAll, addElement, capacity, clear, clone, contains, copyInto, elementAt, elements, ensureCapacity, equals, firstElement, get, hashCode, indexOf, indexOf, insertElementAt, isEmpty, lastElement, lastIndexOf, lastIndexOf, remove, remove, removeAllElements, removeElement, removeElementAt, removeRange, set, setElementAt, setSize, size, subList, toArray, toString, trimToSize

Methods inherited from class java.util.AbstractList<A>

add, add, iterator, listIterator, listIterator, set

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.List<E>

iterator, listIterator, listIterator

Constructor Detail

Stack

public Stack()

Creates an empty Stack.

Method Detail

push

public E push(E item)

Pushes an item onto the top of this stack. This has exactly the same effect as:

 addElement(item)

Parameters:

item - the item to be pushed onto this stack.

Returns:

the item argument.

See Also:

Vector.addElement(E)

pop

public E pop()

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

Returns:

The object at the top of this stack (the last item of the Vector object).

Throws:

EmptyStackException - if this stack is empty.

peek

public E peek()

Looks at the object at the top of this stack without removing it from the stack.

Returns:

the object at the top of this stack (the last item of the Vector object).

Throws:

EmptyStackException - if this stack is empty.

empty

public boolean empty()

Tests if this stack is empty.

Returns:

true if and only if this stack contains no items; false otherwise.

search

public int search(java.lang.Object o)

Returns the 1-based position where an object is on this stack. If the object o occurs as an item in this stack, this method returns the distance from the top of the stack of the occurrence nearest the top of the stack; the topmost item on the stack is considered to be at distance 1. The equals method is used to compare o to the items in this stack.

Parameters:

o - the desired object.

Returns:

the 1-based position from the top of the stack where the object is located; the return value -1 indicates that the object is not on the stack.