java.util

Class 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

    • 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(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.