Is it mandatory to have default constructor?
Strictly speaking, it is never mandatory to have a default constructor. It is mandatory to have a no args constructor (either explicitly declared, or default) …
Why is default constructor needed?
A default constructor is a constructor that either has no parameters, or if it has parameters, all the parameters have default values. If no user-defined constructor exists for a class A and one is needed, the compiler implicitly declares a default parameterless constructor A::A() .
Is default constructor always called?
Constructor has same name as the class itself. … A constructor is automatically called when an object is created. It must be placed in public section of class. If we do not specify a constructor, C++ compiler generates a default constructor for object (expects no parameters and has an empty body).
Can a constructor be empty?
8 Answers. An empty constructor is needed to create a new instance via reflection by your persistence framework. If you don’t provide any additional constructors with arguments for the class, you don’t need to provide an empty constructor because you get one per default.
Why do we need constructors?
Constructors initialize the new object, that is, they set the startup property values for the object. They might also do other things necessary to make the object usable. You can distinguish constructors from other methods of a class because constructors always have the same name as the class.
Can you make a constructor final?
No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. As mentioned previously, the final modifier prevents a method from being modified in a subclass. … In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.
Can we inherit a constructor?
Constructors are not members of classes and only members are inherited. You cannot inherit a constructor. That is, you cannot create a instance of a subclass using a constructor of one of it’s superclasses.
Can constructor be private?
Yes. Class can have private constructor. Even abstract class can have private constructor. By making constructor private, we prevent the class from being instantiated as well as subclassing of that class.
Is overriding possible in Java?
In Java, methods are virtual by default. We can have multilevel method-overriding. Overriding vs Overloading : … Overriding is about same method, same signature but different classes connected through inheritance.
Can a class run without constructor?
It is possible for a class to have no constructor. (An important distinction to draw here is that the JVM does not require all class files to have a constructor; however, any class defined in Java does have a default constructor if a constructor is not explicitly declared.