Module java.base
Package 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:
1.0
See Also:
Serialized Form

  • Constructor Details

    • Stack

      public Stack()
      Creates an empty Stack.

  • Method Details

    • 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.