Can We Override Private Constructor In Java?

Can we inherit class with private constructor in Java?

6 Answers.

Java doesn’t prevent sub-classing of class with private constructors.

This means a private constructor cannot be used in another class file, and a package local constructor cannot be used in another package..

Can a constructor return a 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 constructor throw 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.

Why is enum constructor private?

You need this constructor to be private, because enums define a finite set of values (for example EN_US, EN_UK, FR_FR, FR_BE). If the constructor was public people could potentially create more values (for example invalid/undeclared values such as XX_KK, etc). This would extend the set of initially declared values.

Is constructor by default final?

apply a final keyword to a method means you cannot override that method. but by default in java no constructor can be overridden. so there is no need to use final keyword with a constructor . A constructor can’t inherited so can’t be overridden , so there is no use of making constructor final.

Can you override a constructor Java?

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.

Can we inherit a constructor?

Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass.

Can a constructor be static?

A static constructor does not take access modifiers or have parameters. A class or struct can only have one static constructor. Static constructors cannot be inherited or overloaded. A static constructor cannot be called directly and is only meant to be called by the common language runtime (CLR).

Why constructor is not overridden?

Constructor Overriding is never possible in Java. This is because, Constructor looks like a method but name should be as class name and no return value. Overriding means what we have declared in Super class, that exactly we have to declare in Sub class it is called Overriding.

What is the purpose of a private constructor?

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 constructor be extended?

A class can have multiple constructors, and each constructor can have its own access modifier.

Can constructor be private or protected in Java?

Modifiers public, protected and, private are allowed with constructors. We can use a private constructor in a Java while creating a singleton class. … Since there is only one Singleton instance, any instance fields of a Singleton will occur only once per class, just like static fields.

What happens if we declare constructor as 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.

Can we make constructor final?

No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. … In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.

Why we Cannot override static method?

Static methods cannot be overridden because they are not dispatched on the object instance at runtime. The compiler decides which method gets called. Static methods can be overloaded (meaning that you can have the same method name for several methods as long as they have different parameter types).

Can constructor be private?

Yes, we can declare a constructor as private. If we declare a constructor as private we are not able to create an object of a class. We can use this private constructor in the Singleton Design Pattern.

What is true private constructor?

1. What is true about private constructor? Explanation: Object of private constructor can only be created within class. Private constructor is used in singleton pattern.

Can constructor be virtual?

In C++, the constructor cannot be virtual, because when a constructor of a class is executed there is no virtual table in the memory, means no virtual pointer defined yet. So, the constructor should always be non-virtual. But virtual destructor is possible.