Why do we need an Object parameter for equals method? [duplicate]

Answer 1

The equals method is part of the base Object class in Java and the only way to make benefit of it is to override it. To override it you need to stick to the same signature which will tell any libraries using equals to invoke your method instead of the base one.

Your above code is doing an overloading which is a totally different method to the Java compiler.

Answer 2

It is simple, Object class equals method signature is this

public boolean equals(Object obj)

But if you write equals method with Animal parameter then it will not be the Overridden equals method from object class. and when you try to compare objects by using .equals() Object class equals will be invoked

For this reason and to make it clear it is always recommended to use @Override annotation