java why should equals method input parameter be Object

Question

I'm going through a book on data structures. Currently I'm on graphs, and the below code is for the vertex part of the graph.

class Vertex<E>{
    //bunch of methods

    public boolean equals(Object o){
         //some code
    }
}

When I try to implement this equals method my compiler complains about not checking the type of the parameter and just allowing any object to be sent it. It also does seem a bit strange to me why that parameter shouldn't be a Vertex instead of an Object. Is there a reason why the author does this or is this some mistake or antiquated example?

Answer 1

@Override
public boolean equals(Object obj)
{
     if (!(obj instanceof Vertex)) return false;
     else return // blah blah
}