What is the main method?

Inhaltsverzeichnis:

1. What is the main method?
2. What does Main String [] args mean?
3. Who built Java?
4. Why Main is static in Java?
5. Why constructor is always public?
6. Can a constructor be virtual?
7. Can a constructor return a value?
8. Why can't a constructor be final?
9. Can we inherit a constructor?
10. What is the purpose of a constructor?
11. What is difference between constructor and method?
12. Can you have 2 constructors in Java?

What is the main method?

The main() method is the entry point into the application. The signature of the method is always: public static void main(String[] args) Command-line arguments are passed through the args parameter, which is an array of String s.

What does Main String [] args mean?

public static void main

Who built Java?

James Gosling

Why Main is static in Java?

Java main() method is always static, so that compiler can call it without the creation of an object or before the creation of an object of the class. ... So, the compiler needs to call the main() method. If the main() is allowed to be non-static, then while calling the main() method JVM has to instantiate its class.

Why constructor is 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 a constructor be virtual?

The virtual mechanism works only when we have a base class pointer to a derived class object. 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.

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

Why can't a constructor be final?

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 inherit a constructor?

No, constructors cannot be inherited in Java. 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 a constructor?

The purpose of constructor is to initialize the object of a class while the purpose of a method is to perform a task by executing java code. Constructors cannot be abstract, final, static and synchronised while methods can be. Constructors do not have return types while methods do.

What is difference between constructor and 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. Constructor does not return any value where the method may/may not return a value.

Can you have 2 constructors in Java?

There can be multiple constructors in a class. However, the parameter list of the constructors should not be same. This is known as constructor overloading.