Added Stack Demo

Java/data-structures/StackDemo.java

@@ -0,0 +1,26 @@
+import java.util.Scanner;
+import java.util.Stack;
+
+public class StackDemo {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		Scanner sc=new Scanner(System.in);//declaring a scanner for taking input from user
+		Stack<Integer> stck=new Stack<Integer>();//using inbuilt stack class 
+		System.out.println("Enter how many elements you want to insert into the stack");
+		int n=sc.nextInt();
+
+		System.out.println("Enter "+ n + " elements"); 
+		for(int i=0;i<n;i++)
+		{
+			stck.push(sc.nextInt());//pushing elements into the stack
+		}
+
+		System.out.println("Printing stack elements");
+		while(!stck.empty())
+		{
+			System.out.println(stck.pop()); //it will pop the element from the stack and print it.
+		}
+	}
+
+}