How do you override the equals method on SubClass?
If you create another SubClass without an @Override of the equals method, two SubClass -objects can be equal to each other (if BaseClass. equals check decides so) out of the box, but a SubClass -object will never be equal to a BaseClass -object.
Table of Contents
How do you override the equals method?
The String class overrides the equals method that it inherited from the Object class and implemented the logic to compare the two String objects character by character. The reason the equals method in the Object class references equality is because it doesn’t know how to do anything else.
How do you override the equals method in the Object class?
All classes in Java inherit from the Object class, directly or indirectly (See point 1 of this). The Object class has some basic methods like clone(), toString(), equals(), etc. We can override the equals method in our class to check if two objects have the same data or not.
What is method overriding? Why would you override a method?
Declaring a method in a subclass that is already present in the parent class is known as method overriding. Overriding is done so that a child class can give its own implementation to a method that is already provided by the parent class.
What happens if we don’t override the equals and hashCode methods?
31 answers. You must override hashCode() on all classes that override equals(). Failure to do so will result in a violation of Object’s general contract. hashCode(), which will prevent your class from working correctly in conjunction with all hash-based collections, including HashMap, HashSet, and Hashtable.
When to call super.equals() on subclasses?
I’ve been testing some code and ran into a problem: should I call the super.equals() method in the subclass which can override some of the methods used in the equals() method of the superclass?
How to override a method in a subclass?
So yours would look like this: inventory pack3; public class ItemDetails extends Items { private String Name; private double pNumber, Units, Price; public ItemDetails (String Name, double pNumber, double Units, double Price) { this.Name = Name; this.pNumber = pNumber; this.Units = Units; this.Price = Price; } // getters and setters….
When to use equals method in base class?
That means you can run into problems if your subclass is introducing new fields and you’re comparing an object of the base class (or another subclass that doesn’t override equals) to an object of this subclass.
When to use equals in a subclass in Java?
It is symmetric: for any non-null reference value x and y, x.equals(y) should return true if and only if y.equals(x) returns true. That means you can run into problems if your subclass is introducing new fields and you’re comparing an object of the base class (or another subclass that doesn’t override equals) to an object of this subclass.
