Stack Stracture

package com.coffeland.test;

public class Stack
{
    int Max = 5;
    int top;
    Object[] arr = new Object[5];

    Stack(int maxSize)
    {
        this.Max = maxSize;
        top = -1;
    }

    boolean push(int val)
    {
        // can not push the element into stack if the
        if (top >= (Max-1))
            return false;
        else
        {
            top = top +1;
            arr[top] = val;
            System.out.println(val + " pushed into stack");
            return true;
        }
    }

    Object pop()
    {
        if(top < 0)
            return -1;
        else
        {
            arr[top--] = null;
            return peek();
        }
    }

    Object peek()
    {
        return arr[top];
    }

    void printArr()
    {
        for(Object elem : arr)
        {
            System.out.print (elem + " ");
        }
        System.out.println("-------------------------");
    }

    public static void main(String[] args) {
        Stack s = new Stack(5);
        s.push(10);
        s.push(20);
        s.push(30);
        s.printArr();
        s.pop();
        s.printArr();
    }
}

20 pushed into stack
30 pushed into stack
10 20 30 null null -------------------------
top = 1
10 20 null null null -------------------------

Process finished with exit code 0