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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

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

Public constructors

Stack

added in API level 1
public Stack ()

Creates an empty Stack.

Public methods

empty

added in API level 1
public 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
public 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
public 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
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 E: the item to be pushed onto this stack.

Returns
E the item argument.

search

added in API level 1
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 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.