Check code Above in above code i have created two instances of Equal class at line 9 and 10. I as developer decided that two objects of Equal class are equal if both class have same id(line 2) Now when i use equals method(line 11) it shows that e1 and e2 are different(see o/p). I get o/p "Not Equal" because i have not override equal method in Equal class. So if i want two class with same id should be equal according to equal method then i should override equal method in my class.
hashCode method is Linked with equal method first understand equal method then see why we need to override hashCode method using maps.
When you make 2 objects with the same weight, and invoke equals method
it will give you false. Because the equals is a method you inherit from Object. in equals of Object, it simple estimate if the two references refer to the same object. And a and b refer to different Dog objects. So you get false. To solve that, you should override the equals method. say:
hashCode method is required to be overriden when you override equals, that is a bit complex.. understand the equals first.