Stack_Using _Java

import java.util.*;

class Stack69 {
    int[] arr = new int[20];
    int top = -1;
    int size;

    public void push(int val) {
        if (top == size - 1) {
            System.out.println("Stack Overflow");
        } else {
            top++;
            arr[top] = val;
            System.out.println("Element Pushed!!");
        }
    }

    public int pop() {
        if (top == -1) {
            return -404;
        }
        int temp = arr[top];
        top--;
        return temp;
    }

    public int peek() {
        if (top == -1) {
            return -404;
        }
        return arr[top];
    }

    public void isEmpty() {
        if (top == -1)
            System.out.println("Stack is Empty");
        else
            System.out.println("Stack is not Empty");
    }

    public void show() {
        System.out.print("Stack is:");
        for (int i = 0; i <= top; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }

}

public class Main {
    public static void main(String[] args) {

        Stack69 ob = new Stack69();

        System.out.println("Enter the size of stack:");
        Scanner input = new Scanner(System.in);
        int size = input.nextInt();
        ob.size = size;

        while (true) {
            System.out.println("1...Push");
            System.out.println("2...Pop");
            System.out.println("3...Peek");
            System.out.println("4...IsEmpty");
            System.out.println("5...Show");
            System.out.println("0...Exit");

            System.out.println("Enter the choice:");
            int ch = input.nextInt();

            if (ch == 0) {
                break;
            } else if (ch == 1) {
                System.out.println("Enter the value:");
                int val = input.nextInt();
                ob.push(val);

            } else if (ch == 2) {
                int temp = ob.pop();
                if (temp == -404) {
                    System.out.println("Stack Underflow");
                } else {
                    System.out.println("Element popped:" + temp);
                }
            } else if (ch == 3) {
                int temp = ob.peek();
                if (temp == -404) {
                    System.out.println("Stack is Empty");
                } else {
                    System.out.println("Peek element:" + temp);
                }
            } else if (ch == 4) {
                ob.isEmpty();
            } else if (ch == 5) {
                ob.show();
            }
        }
    }
}