在 equals(Object otherObj) 的实现中使用 getClass.equals(otherObj.getClass())

Question

A boilerplate implementation of an equals(Object otherObj) reads like this:

@Override
    public boolean equals(Object other)
    {
        if(this == other)
            return true;
        if(other == null)
            return false;
        if(this.getClass() != other.getClass())
            return false;
        Employee e = (Employee) other;
        return (Objects.equals(this.name, e.name) && 
                Objects.equals(this.hireDay, e.hireDay) && 
                this.salary == e.salary);      
    }

Can we use:

if(!this.getClass().equals(other.getClass()))

instead?

Answer 1

Class<T> does not override equals and uses the default Object#equals(Object) implementation. Therefore, a.getClass().equals(b.getClass()) is equivalent to a.getClass() == b.getClass()

Object#equals(Object) is implemented as :

 public boolean equals(Object obj) { return (this == obj); }

Since your original condition is this.getClass().= other.getClass() , you have to write .this.getClass().equals(other.getClass()) , if you were to translate it (but that should be very obvious)

Answer 2

This line of code

a.getClass().equals(b.getClass()) 

is equivalent to

a.getClass() == b.getClass()

it can't instead the above equal method.