Quick Answer: Can We Declare A Constructor Private?

Can a constructor throw an exception?

Yes, constructors are allowed to throw an exception in Java.

A Constructor is a special type of a method that is used to initialize the object and it is used to create an object of a class using the new keyword, where an object is also known as an Instance of a class..

Can private constructor class inherited?

If class with private constructor and sealed class cannot be inherited , then what is the use of class which cannot be inherited. … And as said previously private constructor can be excused as we have static classes now. So private constructor + sealed means pure static class. Also sealed class cannot be inherited.

What happens when we override a constructor?

Overriding happens when a subclass has the same name, number/type of parameters, and the same return type as an instance method of the superclass. … Saying that a constructor can be overridden would imply that a superclass constructor would be visible and could be called to create an instance of a subclass.

When should a constructor be private?

Private constructors are used to prevent creating instances of a class when there are no instance fields or methods, such as the Math class, or when a method is called to obtain an instance of a class. If all the methods in the class are static, consider making the complete class static.

Can we inherit a constructor?

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.

Is constructor return any value?

No, constructor does not return any value. While declaring a constructor you will not have anything like return type. In general, Constructor is implicitly called at the time of instantiation.

Can we override private methods?

No, we cannot override private or static methods in Java. Private methods in Java are not visible to any other class which limits their scope to the class in which they are declared.

Can we declare constructor as static?

No, we cannot define a static constructor in Java, If we are trying to define a constructor with the static keyword a compile-time error will occur. In general, static means class level. A constructor will be used to assign initial values for the instance variables.

How do you call a constructor from an inheritance?

This is why the constructor of base class is called first to initialize all the inherited members. For multiple inheritance order of constructor call is, the base class’s constructors are called in the order of inheritance and then the derived class’s constructor.

What happens if we make a constructor private?

The use of private constructor is to serve singleton classes. … Using private constructor we can ensure that no more than one object can be created at a time. By providing a private constructor you prevent class instances from being created in any place other than this very class.

Are constructors always public?

No, Constructors can be public , private , protected or default (no access modifier at all). Making something private doesn’t mean nobody can access it. It just means that nobody outside the class can access it. … Using private constructor we can ensure that no more than one object can be created at a time.

Can private methods be inherited?

Yes. A java private member cannot be inherited as it is available only to the declared java class. Since the private members cannot be inherited, there is no place for discussion on java runtime overloading or java overriding (polymorphism) features.

Can abstract class have constructor?

Yes! Abstract classes can have constructors! Yes, when we define a class to be an Abstract Class it cannot be instantiated but that does not mean an Abstract class cannot have a constructor. Each abstract class must have a concrete subclass which will implement the abstract methods of that abstract class.

Can a constructor return null?

It’s not possible for a constructor to return null , and even if an exception would be thrown from the constructor, the next line won’t be called. From section 15.9. 4 of the JLS: The value of a class instance creation expression is a reference to the newly created object of the specified class.

What is call override?

Overriding is done so that a child class can give its own implementation to a method which is already provided by the parent class. In this case the method in parent class is called overridden method and the method in child class is called overriding method.

Can we declare constructor as 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.

Can we override constructor?

Constructor looks like method but it is not. It does not have a return type and its name is same as the class name. But, a constructor cannot be overridden. If you try to write a super class’s constructor in the sub class compiler treats it as a method and expects a return type and generates a compile time error.