MyStack

public class MyStack <T>{
    Node top;
    int size;

    public MyStack() {
        top = null;
        size = 0;
    }
    
    int getSize(){
        return size;
    }
    void push(T value){
        Node nodo = new Node(value);
        if(top == null)
            top = nodo;
        else {
            nodo.next = top;
            top = nodo;
        }
        size++;
    }
    // Extra methods
    void pushButtom(T value){
        MyStack stk = new MyStack();
        stk.push(value);
        this.Reverse();
        
        while(!this.isEmpty()){
            stk.push(this.pop()); 
        }
        
        this.top = stk.top;
    }
    
    T pop(){
        if(top == null)
            throw new ArrayIndexOutOfBoundsException();
        T value = (T) top.data;
        top = top.next;
        size--;
        return value;
    }
    
    T peek(){
        return (T) top.data;
    }
    
    boolean isEmpty(){
        return top == null;
    }
    
    void Reverse(){
        MyStack stk = new MyStack();
        while(!isEmpty()){
            stk.push(pop());
        }
        this.top = stk.top;
    }
   
    @Override
    public String toString(){
         Node curr = top;
            String str = "[";
            while(curr != null){
                str += curr.data;
                if(curr.next!= null)
                    str += ", ";
                curr = curr.next;
            }
            str += "]";
            return str;
    } 
}