Quick Answer: Should Constructors Be Private Or Public?

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 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.

What happens if we override private method?

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.

Why we use public private and protected?

A public member is accessible from anywhere outside the class but within a program. … A protected member variable or function is very similar to a private member but it provided one additional benefit that they can be accessed in child classes which are called derived classes.

Can you use this () and super () both in a constructor?

Because if you use this() and super() together in a constructor it will give compile time error. Because this() and super() must be the first executable statement. If you write this() first than super() will become the second statement and vice-versa. That’s why we can’t use this() and super() together.

What happens if we make a 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 use of private?

We can’t assign private to outer class and interface. The best use of private keyword is to create a fully encapsulated class in Java by making all the data members of that class private. If we make any class constructor private, we cannot create the instance of that class from outside the class.

Can a constructor be overloaded?

Yes! Java supports constructor overloading. In constructor loading, we create multiple constructors with the same name but with different parameters types or with different no of parameters.

Can 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 we override static method?

Can we Override static methods in java? We can declare static methods with the same signature in the subclass, but it is not considered overriding as there won’t be any run-time polymorphism. Hence the answer is ‘No’.

Is constructor can 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.

Should methods be private or public?

The rule is that a method should be made provided unless it is needed. One of the main reasons for this is that in a future release of an API etc., you can always make a private function public, but you can almost never make a previous public function private without breaking existing code.

Can a constructor be 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.

Can we create a private class in Java?

No, we cannot declare a top-level class as private or protected. It can be either public or default (no modifier).

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).

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 private method call public method?

If a private method must call a public method, then the content of the public method should be taken and placed in a private method, which both methods can then call. … Public methods provide access to the outside world. There’s no reason to walk back outside when you’re already inside.

Are private methods final?

When we use final specifier with a method, the method cannot be overridden in any of the inheriting classes. Methods are made final due to design reasons. Since private methods are inaccessible, they are implicitly final in Java.

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 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.

What is the point of private variables?

Private variables ensure that later references outside the scope of an object or function won’t inadvertently affect other variables. For large programming projects, this can help avoid a lot of interesting problems (that are usually not caught by compiler).

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.

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.

What is private keyword in Java?

The private keyword is an access modifier used for attributes, methods and constructors, making them only accessible within the declared class.

What is the difference between private and protected?

The class members declared as private can be accessed only by the functions inside the class. … The class member declared as Protected are inaccessible outside the class but they can be accessed by any subclass(derived class) of that class.

Can we extend a class with private constructor?

There is no way out. You have to create an available ( protected , public or default) super constructor to be able to extend test . … When you have a class with only private constructors, you can also change the class to final because it can’t be extended at all.

Can we override private and final methods?

No, We can not override private method in Java, just like we can not override static method in Java. … private methods are not even visible to Child class, they are only visible and accessible in the class on which they are declared. private keyword provides highest level of Encapsulation in Java.