class Stack<E> in Java

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class Stack in Java

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обновлено: 6 October 2026

class Stack<E> extends class Vector<E> with the algorithm "last in - first out":
Each new element is placed at the very top.
The first element is the one at the very top.

Stack is fully synchronized (thread-safe).

Class Stack extends class Vector with five functions that allow a vector to be treated as a stack:

Java

push(E item) // Add a new element and the element is placed at the very top
E pop() // Pull out the element, take the element that is at the very top and delete it
E peek() // Look at the element that is at the very top, the element is not deleted
boolean empty() // checks if this stack is empty
int search(Object o) // Look for the item, the position is returned starting with 1

Example

Java Creating a new Java console application ... and write the code

package org.example;
import java.util.Stack;

public class Program {
     public static void main(String[] args)
     {
          Stack<String> myList1 = new Stack<String>();

          // Add the element to the top
          myList1.push("Car");
          // myList1 = ["Car"]

          // Add the element to the top
          myList1.push("House");
          // myList1 = ["Car", "House"]

          // Add the element to the top
          myList1.push("Book");
          // myList1 = ["Car", "House", "Book"]

          // View item at the top
          String elem = myList1.peek();
          // elem = "Book"
          // myList1 = ["Car", "House", "Book"]

          // Take the element from the top, the element is deleted
          elem = myList1.pop();
          // elem = "Book"
          // myList1 = ["Car", "House"]

          /////// can call Vector functions /////////

          // Add an element to the end
          myList1.add("Notebook");
          // myList1 = ["Car", "House", "Notebook"]

          // View item by index
          elem = myList1.get(1);
          // elem = "House"
          // myList1 = ["Car", "House", "Notebook"]

          // Insert element by index 1
          myList1.add(1, "Airplane");
          // myList1 = ["Car", "Airplane", "House", "Notebook"]

          // Delete item by index
          myList1.remove(1);
          // myList1 = ["Car", "House", "Notebook"]
     }
}

Kotlin Creating a new Kotlin console application ... and write the code

import java.util.Stack

fun main() {

     val myList1 = Stack<String>()

     // Add the element to the top
     myList1.push("Car")
     // myList1 = ["Car"]

     // Add the element to the top
     myList1.push("House")
     // myList1 = ["Car", "House"]

     // Add the element to the top
     myList1.push("Book")
     // myList1 = ["Car", "House", "Book"]

     // View item at the top
     var elem = myList1.peek()
     // elem = "Book"
     // myList1 = ["Car", "House", "Book"]

     // Take the element from the top, the element is deleted
     elem = myList1.pop()
     // elem = "Book"
     // myList1 = ["Car", "House"]

     /////// can call Vector functions /////////

     // Add an element to the end
     myList1.add("Notebook")
     // myList1 = ["Car", "House", "Notebook"]

     // View item by index
     elem = myList1[1]
     // elem = "House"
     // myList1 = ["Car", "House", "Notebook"]

     // Insert element by index 1
     myList1.add(1, "Airplane")
     // myList1 = ["Car", "Airplane", "House", "Notebook"]

     // Delete item by index
     myList1.removeAt(1)
     // myList1 = ["Car", "House", "Notebook"]
}

Documentation

Java

class Stack<E> extends Vector<E>
{
     public Stack() {
     }

     public E push(E item) {
          addElement(item);

          return item;
     }

     public synchronized E pop() {
          E obj;
          int len = size();

          obj = peek();
          removeElementAt(len - 1);

          return obj;
     }

     public synchronized E peek() {
          int len = size();

          if (len == 0)
               throw new EmptyStackException();
          return elementAt(len - 1);
     }

     public boolean empty() {
          return size() == 0;
     }

     public synchronized int search(Object o) {
          int i = lastIndexOf(o);

          if (i >= 0) {
               return size() - i;
          }
          return -1;
     }
}

Learn more about methods in the Java documentation:https://docs.oracle.com ...

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