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Stack

public class Stack
extends Vector<E>

java.lang.Object
   ↳ java.util.AbstractCollection<E>
     ↳ java.util.AbstractList<E>
       ↳ java.util.Vector<E>
         ↳ java.util.Stack<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>();

Summary

Inherited fields

From class java.util.Vector
From class java.util.AbstractList

Public constructors

Stack()

Creates an empty Stack.

Public methods

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.

Inherited methods

From class java.util.Vector
From class java.util.AbstractList
From class java.util.AbstractCollection
From class java.lang.Object
From interface java.util.List
From interface java.util.Collection
From interface java.lang.Iterable

Public constructors

Stack

Added in API level 1
Stack ()

Creates an empty Stack.

Public methods

empty

Added in API level 1
boolean empty ()

Tests if this stack is empty.

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

peek

Added in API level 1
E peek ()

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

Returns
E the object at the top of this stack (the last item of the Vector object).
Throws
EmptyStackException if this stack is empty.

pop

Added in API level 1
E pop ()

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

Returns
E The object at the top of this stack (the last item of the Vector object).
Throws
EmptyStackException if this stack is empty.

push

Added in API level 1
E push (E item)

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

 addElement(item)

Parameters
item E: the item to be pushed onto this stack.
Returns
E the item argument.

See also:

search

Added in API level 1
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 Object: the desired object.
Returns
int 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.
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