Can a constructor be declared static?

Java constructor can not be static

One of the important property of java constructor is that it can not be static. We know static keyword belongs to a class rather than the object of a class. A constructor is called when an object of a class is created, so no use of the static constructor.

Can a constructor be declared static or final?

No Constructors can NEVER be declared as final. Your compiler will always give an error of the type "modifier final not allowed" Final, when applied to methods, means that the method cannot be overridden in a subclass. Constructors are NOT ordinary methods.

Can constructor be static and non static?

Static constructor can initialize only static variable but non-static constructor can initialize both static and non-static variable. Static constructor do not have any access specifier but non-static constructor have access specifier.

Can we declare constructor as static in C++?

The constructor member function constructs the object as specified, using an existing allocation -- i.e. this is present. static member functions specify no storage to an object, so there is no associated instance to construct -- i.e. this is absent. Therefore, you cannot specify a static constructor.

Is default constructor private?

A constructor is a special member function of a class which initializes objects of a class. In C++, constructor is automatically called when object of a class is created. By default, constructors are defined in public section of class.

Can a Constructor be static in Java ?

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.

Can we call constructor from static method?

Static method cannot cannot call non-static methods. Constructors are kind of a method with no return type.

Can we overload constructor?

Constructors can be overloaded in a similar way as function overloading. Overloaded constructors have the same name (name of the class) but the different number of arguments. Depending upon the number and type of arguments passed, the corresponding constructor is called.

Can constructor be overridden?

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 a constructor be abstract?

You can't have an abstract constructor, as abstract means you need to provide the implementation for that at some point of time in your subclass. But you cannot override constructor. There will be no point in having an abstract constructor : Since the constructor needs to be of the same name as of class.

Can constructor be inherited?

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

Why constructor can not be final static or abstract?

The child class inherits all the members of the superclass except the constructors. In other words, constructors cannot be inherited in Java therefore you cannot override constructors. So, writing final before constructors makes no sense. Therefore, java does not allow final keyword before a constructor.

Can we overload main method?

Yes, we can overload the main method in Java, but When we execute the class JVM starts execution with public static void main(String[] args) method.

Can we overload constructor in derived class?

Since the constructors can't be defined in derived class, it can't be overloaded too, in derived class.

Can final methods be overloaded?

Yes, overloading a final method is perfectly legitimate.

Can constructor have return type?

No, constructor does not have any return type in 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. Mostly it is used to instantiate the instance variables of a class.

Can constructor have parameters?

Constructors can also take parameters, which is used to initialize attributes.

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

What happens if we declare constructor as static?

If we declare a constructor as static, then it can not be accessed by its subclasses and will belong to a class level only. The program will not be compiled and throw a compile-time error.

Can we have constructor in static class in Java?

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.

Can a constructor be virtual?

Virtual Constructor in C++

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.

Can a constructor be 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. So private constructor is useful too.

Can a constructor be recursive?

If a constructor calls itself, then the error message “recursive constructor invocation” occurs. The following program is not allowed by the compiler because inside the constructor we tried to call the same constructor. The compiler detects it instantly and throws an error.

Can we execute a class without a main method?

Yes, we can execute a java program without a main method by using a static block. Static block in Java is a group of statements that gets executed only once when the class is loaded into the memory by Java ClassLoader, It is also known as a static initialization block.

Can we have 2 main methods in Java?

From the above program, we can say that Java can have multiple main methods but with the concept of overloading. There should be only one main method with parameter as string[ ] arg.