I am getting an error, please have a look

i am getting an error while submittingā€¦please have a look on code ā€”>>

import java.util.*;

public class Main {

static Scanner s = new Scanner(System.in);

public static void main(String args[]) throws Exception {
	// Your Code Here

	int q = s.nextInt();
	Main obj = new Main();
	StacksUsingArrays stack = obj.new StacksUsingArrays();
	Calculate(stack, q);
}

public static void Calculate(StacksUsingArrays stack, int q) throws Exception {
	while (q-- > 0) {
		int type = s.nextInt();
		if (type == 1) {
			if(!stack.isEmpty()) {
				System.out.println(stack.pop());
			} else {
				System.out.println("Stack is Empty");
			}
		} else {
			stack.push(s.nextInt());
		}
	}
}

private class StacksUsingArrays {
	private int[] data;
	private int tos;

	public static final int DEFAULT_CAPACITY = 10;

	public StacksUsingArrays() throws Exception {
		// TODO Auto-generated constructor stub
		this(DEFAULT_CAPACITY);
	}

	public StacksUsingArrays(int capacity) throws Exception {
		if (capacity <= 0) {
			System.out.println("Invalid Capacity");
		}
		this.data = new int[capacity];
		this.tos = -1;
	}

	public int size() {
		return this.tos + 1;
	}

	public boolean isEmpty() {
		if (this.size() == 0) {
			return true;
		} else {
			return false;
		}
	}

	public void push(int item) throws Exception {
		if (this.size() == this.data.length) {

			int[] temp = new int[2 * data.length];
			for (int i = 0; i < data.length; i++) {
				temp[i] = data[i];
			}

			data = temp;
		}
		this.tos++;
		this.data[this.tos] = item;
	}

	public int pop() throws Exception {
		if (this.size() == 0) {
			throw new Exception("Stack is Empty");
		}
		int retVal = this.data[this.tos];
		this.data[this.tos] = 0;
		this.tos--;
		return retVal;
	}

	public int top() throws Exception {
		if (this.size() == 0) {
			throw new Exception("Stack is Empty");
		}
		int retVal = this.data[this.tos];
		return retVal;
	}

	public void display() throws Exception {
		if (this.size() == 0) {
			throw new Exception("Stack is Empty");
		}
		for (int i = this.tos; i >= 0; i--) {
			System.out.println(this.data[i]);
		}

	}

}

}

You have to print ā€œNo Codeā€ when stack is empty and student wants to buy course.

still getting errorā€¦removed the ā€˜elseā€™ condition after : ā€˜if (!stack.isEmpty)ā€™

if you pop from an empty stack, that may result in a run error
go through this code