How are this () and super () used with constructors?

How are this () and super () used with constructors?

How are this () and super () used with constructors?

super() as well as this() both are used to make constructor calls. super() is used to call Base class's constructor(i.e, Parent's class) while this() is used to call current class's constructor. ... super() is use to call Base class's(Parent class's) constructor.

Where super () can be used within a constructor?

When used in a constructor, the super keyword appears alone and must be used before the this keyword is used. The super keyword can also be used to call functions on a parent object.

Can a constructor be private and how are this () and super () method used with constructor?

Yes it can. A private constructor would exist to prevent the class from being instantiated, or because construction happens only internally, e.g. a Factory pattern.

Can you use this in a constructor?

this() can be used to invoke current class constructor. this can be passed as an argument in the method call. this can be passed as argument in the constructor call. this can be used to return the current class instance from the method.

Why is it not possible to use this () and super () in the same constructor?

Because this() and super() must be the first executable statement. If you write this() first than super() will become the second statement and vice-versa. That's why we can't use this() and super() together. both this() and super() can not be used together in constructor.

Why super is used in constructor?

We use super keyword to call the members of the Superclass. As a subclass inherits all the members (fields, methods, nested classes) from its parent and since Constructors are NOT members (They don't belong to objects. They are responsible for creating objects), they are NOT inherited by subclasses.

What is the rule for a super reference in a constructor?

What is the rule for a super reference in a constructor? It must be in the parent class' constructor. It must be the last line of the constructor in the child class.

What is the difference between using super and super () in a Java method?

The super keyword in Java is a reference variable that is used to refer parent class objects. The super() in Java is a reference variable that is used to refer parent class constructors. super can be used to call parent class' variables and methods.

Can you use this () and super () both in a constructor justify the reason with example?

both this() and super() can not be used together in constructor. this() is used to call default constructor of same class.it should be first statement inside constructor. super() is used to call default constructor of base class.it should be first statement inside constructor.

Can you use this () in a constructor if yes then how?

Calling a method using this keyword from a constructor Yes, as mentioned we can call all the members of a class (methods, variables, and constructors) from instance methods or, constructors.

Can a constructor call both this and Super?

  • Both this () and super () are constructor calls. Constructor call must always be the first statement. So we can not have two statements as first statement, hence either we can call super () or we can call this () from the constructor, but not both.

Can you use both constructors in a single line?

  • And that's the reason why we can't use both in a single constructor because you can write only one thing in your first line. Because it doesn't make sense. A constructor has to either call this () or super () (implicitly or explicitly). this () calls another constructor which has to call either this () or super () etc as before.

Which is the first call in a constructor?

  • Both this () and super () are constructor calls. Constructor call must always be the first statement. So you either have super () or this () as first statement. Both this () and super () are constructor calls, and constructor call must be the first (and only first) call in a constructor.

What's the difference between Super ( ) and this ( )?

  • There is a difference between super() and this() . Constructor must always be the first statement. this(...) will call another constructor in the same class whereas super() will call a super constructor. If there is no super() in a constructor the compiler will add one implicitly.

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