Can constructor be inherited through a subclass that calls the superclass constructor?
Constructor is a block of statements that permits you to create an object of specified class and has similar name as class with no explicit or specific return type. No, constructor cannot be inherited in java. In case of inheritance, child/sub class inherits the state (data members) and behavior (methods) of parent/super class.
But it does not inherits the constructor because of the following reason: If parent class constructor is inherited in child class, then it can not be treated as constructor because constructor name must be same as of class name. It will be treated as a method but now the problem is, method should have explicit return type which inherited parent class constructor can not have. Output SubClass.java:27: error: cannot find symbol object1.SuperClass(); // not allowed ^ symbol: method SuperClass() location: variable object1 of type Main SubClass.java:28: error: incompatible types: SuperClass cannot be converted to Main SubClass object2 = new SuperClass(); // not allowed ^ 2 errors Java interview questions on constructor
We prefer inheritance to reuse the code available in existing classes. In Java, Inheritance is the concept in which one class inherits the properties of another class. In the below example there are two classes Programming and DP while Programming is Parent class and DP is child class. From the main class, we have created an object of DP i.e. child class as it also allows us to access the methods from its parent class, but if we create an object of Parent class(Programming) then we cannot access the methods or objects from its child class. After creating an object of child class we have first called a method from child class and then called a method from the parent class. This doesn’t matter as we can call the objects in any order. Java
Output : DP Programming Constructor InheritanceIn the below example, we have created a parent and child class. Here, we have created an object of the child class, as the constructor will call itself on creating an object we need not mention anything. After creating an object of child class the constructor is expected to print the output from its own class, but from the output, we can identify that Parent class got executed and then child class got executed, this is because we have created a constructor for inherited class and every class contains a super() by default, as we are calling an inherited class it contains super() in its first line and calls the Parent class. Java
Constructor Overloading With SuperIn the below example we have used the constructor overloading concept, and we have created an object of child class and after calling the constructor of child class the first line in it is super(10, 20) which says that call the matching constructor from the parent class, if we do not mention that line, by default it calls the super() with no parameterized constructor from Parent class. Java
Output: Programming + + DP AnalogyLet’s look at the below snippet,
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Output : Programming DP + Can we call a superclass constructor from the class constructor?To explicitly call the superclass constructor from the subclass constructor, we use super() . It's a special form of the super keyword. super() can be used only inside the subclass constructor and must be the first statement.
Can constructors be inherited through?No, constructors cannot be inherited in Java. In inheritance sub class inherits the members of a super class except constructors. In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.
Can superclass inherit subclass method?No, it is not possible to call sub class method inside super class. Though it is possible to call different implementations of the same method in a client code while you have a variable with a super class type and instantiate it with either super class or sub class objects. It is called polymorphism.
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