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Can we assign parent object to child objects?
The reference variable of the Parent class is capable to hold its object reference as well as its child object reference. In Java, methods are virtual by default (See this for details).
When child class object is assigned to parent class is called?
This is called subtype polymorphism. Your updated question asks why Child. salary is not accessible when the Child object is stored in a Parent reference. The answer is the intersection of “polymorphism” and “static typing”.
How do you call parent class method from child object?
Super Keyword in Java
- The super keyword in java is a reference variable that is used to refer parent class objects.
- Use of super with variables: This scenario occurs when a derived class and base class has same data members.
- Use of super with methods: This is used when we want to call parent class method.
Can child class create object of parent class?
The parent class can hold reference to both the parent and child objects. If a parent class variable holds reference of the child class, and the value is present in both the classes, in general, the reference belongs to the parent class variable.
How does a child class reference the parent class?
The parent class can hold reference to both the parent and child objects. If a parent class variable holds reference of the child class, and the value is present in both the classes, in general, the reference belongs to the parent class variable. This is due to the run-time polymorphism characteristic in Java.
Can an interface have main () method?
Yes, from Java8, interface allows static method. So we can write main method and execute it.
When do parent and child classes have the same reference?
If a parent reference variable is holding the reference of the child class and we have the “value” variable in both the parent and child class, it will refer to the parent class “value” variable, whether it is holding child class object reference.
Why do we assign a parent reference to the child object in Java?
Because Java is statically typed at compile time you get certain guarantees from the compiler but you are forced to follow rules in exchange or the code won’t compile. Here, the relevant guarantee is that every instance of a subtype (e.g. Child) can be used as an instance of its supertype (e.g. Parent ).
Why are child and parent classes the same in Java?
This is because the parent reference variable can only access fields that are in the parent class. Thus the type of reference variable decides which version of “value” will be called and not the type of object being instantiated. It is because compiler uses special run-time polymorphism mechanism only for methods.
How to access child class members in Java?
The reference holding the child class object reference will not be able to access the members (functions or variables) of the child class. It is because compiler uses special run-time polymorphism mechanism only for methods. It is possible to access child data members using parent pointer with typecasting.