Stacks using Arrays

/*Copyrights to vsdevelopers.io*/
/*For more programs visit vsdevelopers.io */
/*Java program for stack operations using array*/
/*The operations are Create, Insert,Delete, Search, Destroy*/
import java.util.Scanner;

public class VSDStackArray {
	static Scanner sc = new Scanner(System.in);

	static int size;// size of stack
	static int stack[];// stack array
	static int top = -1;// top of the stack

	// Function to create a stack
	public static void VSDcreateStack() {
		System.out.println("Enter size of stack");
		size = sc.nextInt();
		stack = new int[size];
	}

	// Function to insert element into the stack
	public static void VSDpush() {
		if (stack == null)// Checking whether the stack exists or not
		{
			System.out.println("Stack doesnot exist, Create the stack");
			return;
		}
		if (top == size - 1) // Checking for stack overflow
			System.out.println("Cannot insert the element, Stack is full");
		else {
			System.out.println("Please Enter element to insert:");
			int element = sc.nextInt();
			stack[++top] = element;// Inserting the element and updating the top
		}
		VSDprintStack();
	}

	// Function to delete element into the stack
	public static void VSDpop() {
		if (stack == null)// Checking whether the stack exists or not
		{
			System.out.println("Stack doesnot exist, Create the stack");
			return;
		}
		if (top == -1)// Checking if stack is empty
			System.out.println("Stack is empty");
		else {
			int element = stack[top];
			top--; // Deleting the element and updating the top
			System.out.println("The deleted element is:" + element);

		}

	}

	// Function to search element in stack
	public static void VSDsearch() {
		if (stack == null)// Checking whether the stack exists or not
		{
			System.out.println("Stack doesnot exist, Create the stack");
			return;
		}
		if (top == -1)// Checking if stack is empty
			System.out.println("Stack is empty");
		else {
			System.out.println("Please Enter element to serach:");
			int element = sc.nextInt();
			int flag = 0;// For marking presence of elements
			for (int i = 0; i <= top; i++) {
				if (element == stack[i]) {
					System.out.println("Element is present at index: " + i);
					flag = 1;
				}
			}
			if (flag == 0)
				System.out.println("Element is not present in stack");
		}

	}

	// Function to destroy stack
	public static void VSDdestroy() {
		stack = null;
		System.out.println("Stack is destroyed");
	}

	// Function to print the stack
	public static void VSDprintStack() {
		System.out.println("Now the stack is");
		if (top == -1)
			System.out.println("Stack is Empty!!!");
		for (int i = top; i >= 0; i--)
			System.out.println(stack[i]);

	}

	// Function to take user input
	public static void VSDuserInput() {
		System.out.println("Please Enter stack operation from:");
		System.out.println("Create Insert Delete Search Destroy");
		String choice = sc.next();
		switch (choice) {
		case "Create":
		case "create":
			VSDcreateStack();
			break;
		case "Insert":
		case "insert":
			VSDpush();
			break;
		case "Delete":
		case "delete":
			VSDpop();
			break;
		case "Search":
		case "search":
			VSDsearch();
			break;
		case "Destroy":
		case "destroy":
			VSDdestroy();
			break;
		}
		VSDuserChoice();
	}

	public static void VSDuserChoice() {
		System.out.println("For performing operations enter y else enter n");
		char ch = sc.next().charAt(0);
		if (ch == 'Y' || ch == 'y')
			VSDuserInput();
		else
			return;
	}

	public static void main(String args[]) {
		VSDcreateStack();// Creating stack initially
		VSDuserInput();// Taking user input to perform stack operations
	}
}