Question: Can We Make Constructor Private?

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..

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.

Can private constructor class inherited?

If a class has one or more private constructor and no public constructor then other classes are not allowed to create instance of this class; this means you can neither create the object of the class nor can it be inherited by other classes.

Can constructor have return type?

No, constructor does not have any return type in Java. … It does not have a return type and its name is same as the class name. Mostly it is used to instantiate the instance variables of a class. If the programmer doesn’t write a constructor the compiler writes a constructors on his behalf.

Why we Cannot make constructor final?

A constructor is never inherited to an another class so it doesn’t need to be marked final. Hey, The constructor cannot be final because the constructor cannot be inherited and in constructor values are initialized to the variable so by this variables changes every time and yes it cannot be inherited.

Can we override private methods?

No, a private method cannot be overridden since it is not visible from any other class. You have declared a new method for your subclass that has no relation to the superclass method.

Can constructor be a friend function?

It is possible but makes no sense, because a friend function is external but must call class code.

What happens if we make constructor private?

4 Answers. It means that (without reflection) constructor wont be accessible outside of your class so other classes wont be able to call it. Only members of your class will be bale to create its object.

What is the true about 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 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.

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 a constructor call another constructor?

Yes, any number of constructors can be present in a class and they can be called by another constructor using this() [Please do not confuse this() constructor call with this keyword]. this() or this(args) should be the first line in the constructor. This is known as constructor overloading.

Does 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. And it is not a method, its sole purpose is to initialize the instance variables.

Should a constructor be public or private?

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. So private constructor is useful too.

Can a constructor be final?

No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. … But, 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.

What is the purpose of 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.

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).

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.

Can a 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.

What is the difference between a constructor and a method?

Constructor is used to initialize an object whereas method is used to exhibits functionality of an object. Constructors are invoked implicitly whereas methods are invoked explicitly. … In the case of a method, no default method is provided. Constructor should be of the same name as that of class.

Why are constructors always public?

You make a constructor public if you want the class to be instantiated from any where. You make a constructor protected if you want the class to be inherited and its inherited classes be instantiated. … Example of usage of private constructor is singleton design pattern.