java.util
Class Stack<E>

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractList<E>
          java.util.Vector<E>
              java.util.Stack<E>

All Implemented Interfaces:

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

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.

A more complete and consistent set of LIFO stack operations is provided by the Deque interface and its implementations, which should be used in preference to this class. For example:

 Deque<Integer> stack = new ArrayDeque<Integer>(); 

Since:

JDK1.0

See Also:

Serialized Form

Field Summary

 

Fields inherited from class java.util. Vector
capacityIncrement , elementCount , elementData

 

Fields inherited from class java.util. AbstractList
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 ( Object  o)           Returns the 1-based position where an object is on this stack.

 

Methods inherited from class java.util. Vector

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

 

Methods inherited from class java.util. AbstractList
iterator , listIterator , listIterator

 

Methods inherited from class java.lang. Object
finalize , getClass , notify , notifyAll , wait , wait , wait

 

Methods inherited from interface java.util. List
iterator , listIterator , listIterator

 

Constructor Detail

Stack

public Stack()

Creates an empty Stack.

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(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.