Collection Framework Stack

Stack Class :

Stack is a predefined package in java.util package .It allows duplicate elements along with unique elements and it works on last in first out manner.That means the element which inserted at last, that can be retrieved first. Stack class offers the following predefined methods.

Stack Methods

1.Push
2.Pop
3.Peek
4.Empty
5.Search

Key Points

What is Collections

Stack Push Method:

It is used to push a new element on top of stack

Program
Online Compiler



Import  java.util.*;	
	class StackPush
	{
	void list()
	{
	Stack<Integer> al=new Stack<Integer>();
	al.push(20);
	al.push(10);
	al.push(30);
	al.push(40);
	al.push(50);
	System.out.println("The List Items Are "+al);
	}
	}
	class Main
	{
	public static void main(String aargs[])
	{
	StackPush d=new StackPush();
	d.list();
	}
	}

Output:

Stack Pop Method

Which will be used to remove the element from the top of stack.

Program
Online Compiler

import java.util.*;	
	class StackPop
	{
	void list()
	{
	Stack<Integer> al=new Stack<Integer>();
	al.push(20);
	al.push(10);
	al.push(30);
	al.push(40);
	al.push(50);
	System.out.println("The List Items Are "+al);
	al.pop();
	System.out.println("After Poping The List Items Are "+al);
	}
	}
	
	class Main
	{
	public static void main(String aargs[])
	{
	StackPop d=new StackPop();
	d.list();
	}
	}

Output:

Stack Peek Method

It returns the type of the stack element.

Program
Online Compiler

import java.util.*;	
	class StackPeek
	{
	void list()
	{
	Stack<Integer> al=new Stack<Integer>();
	al.push(20);
	al.push(10);
	al.push(30);
	al.push(40);
	al.push(50);
	System.out.println("The List Items Are "+al);
	
	System.out.println(al.peek());
	}
	}
	
	class Main
	{
	public static void main(String aargs[])
	{
	StackPeek d=new StackPeek();
	d.list();
	}
	}

Output:

Stack Empty Method

It returns true in the given stack is empty otherwise false.

Program
Online Compiler

import java.util.*;	
	class StackEmpty
	{
	void list()
	{
	Stack<Integer> al=new Stack<Integer>();
	al.push(20);
	al.push(10);
	al.push(30);
	al.push(40);
	al.push(50);
	System.out.println("The List Items Are "+al);
	
	System.out.println(al.empty());
	}
	}
	
	class Main
	{
	public static void main(String aargs[])
	{
	StackEmpty d=new StackEmpty();
	d.list();
	}
	}

Output:

Stack Search Method

Which can be used to return index value of the given element otherwise it returns -1

Program
Online Compiler

import java.util.*;	
	class StackSearch
	{
	void list()
	{
	Stack<Integer> al=new Stack<Integer>();
	al.push(20);
	al.push(10);
	al.push(30);
	al.push(40);
	al.push(50);
	System.out.println("The List Items Are "+al);
	
	System.out.println(al.search(500));
	}
	}
	
	class Main
	{
	public static void main(String aargs[])
	{
	StackSearch d=new StackSearch();
	d.list();
	}
	}