Can we define subclass first and superclass later in Java?
Classes in Java exist in a hierarchy. A class in Java can be declared as a subclass of another class using the extends keyword. A subclass inherits variables and methods from its superclass and can use them as if they were declared within the subclass itself: … A subclass can be further subclassed.
Can you assign a subclass to a superclass in Java?
Yes, it is. Let a superclass and a subclass be given. If you declare a reference to a superclass, then this reference can be assigned the value of a reference to a subclass that inherits this superclass. For example.
Can we assign superclass object to subclass?
No. It makes zero sense to allow that. The reason is because subclasses generally define additional behavior. If you could assign a superclass object to a subclass reference, you would run into problems at runtime when you try to access class members that don’t actually exist.
Can a class be superclass and subclass at same time?
Absolutely, yes. Classes can (and quite commonly are, if you look in the Java class hierarchy) be sub and superclasses at the same time.
Do Superclasses need constructors?
A subclass needs a constructor if the superclass does not have a default constructor (or has one that is not accessible to the subclass). If the subclass has no constructor at all, the compiler will automatically create a public constructor that simply calls through to the default constructor of the superclass.
Does a subclass inherit both fields and methods?
A subclass inherits all the members (fields, methods, and nested classes) from its superclass. Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass.
Can subclass override the methods of superclass?
A subclass within the same package as the instance’s superclass can override any superclass method that is not declared private or final. A subclass in a different package can only override the non-final methods declared public or protected.
Is a subclass object also a superclass object?
A superclass object is a subclass object. … The class following the extends keyword in a class declaration is the direct superclass of the class being declared. d. Java uses interfaces to provide the benefits of multiple inheritance.
Can we inherit static variables in Java?
The static keyword is used to create methods that will exist independently of any instances created for the class. Static methods do not use any instance variables of any object of the class they are defined in. We can inherit static methods in Java. …
Can you convert a superclass reference into a subclass reference?
Can you convert a superclass reference into a subclass reference? Yes. We can always convert ( Cast ) a superclass reference into a subclass reference.
Is superclass instance of subclass?
When one class inherits from another class in Java, the two classes take on certain roles. The class that extends (inherits from another class) is the subclass and the class that is being extended (the class being inherited from) is the superclass . In other words, the subclass extends the superclass.
What happens if superclass and subclass having same field name?
Java interview questions on Inheritance
Are interfaces also inherited from Object class? … Are constructors inherited in java? What happens if both superclass and subclass have a field with same name? Are static members inherited to subclasses in java?
Can a class have 2 Superclasses?
6 Answers. Classes in Java can only extend one class, your trying to extend two.
What happens if superclass and subclass having same variable name?
If your subclass defines a member variable with the same name as a member variable in its superclass, the variable in the subclass hides the one in the superclass. Thus, the subclass does not inherit the variable from its superclass.