When is default constructor created

If you don't provide a static constructor to initialize static fields, the C compiler initializes static fields to their default value as listed in the Default values of C types article. You can also define a static constructor with an expression body definition, as the following example shows.

For more information and examples, see Static Constructors. How to write a copy constructor. Learn more about visibility modifiers. A class can also declare secondary constructors , which are prefixed with constructor :. If the class has a primary constructor, each secondary constructor needs to delegate to the primary constructor, either directly or indirectly through another secondary constructor s.

Delegation to another constructor of the same class is done using the this keyword:. Code in initializer blocks effectively becomes part of the primary constructor. Delegation to the primary constructor happens as the first statement of a secondary constructor, so the code in all initializer blocks and property initializers is executed before the body of the secondary constructor.

Even if the class has no primary constructor, the delegation still happens implicitly, and the initializer blocks are still executed:. If a non-abstract class does not declare any constructors primary or secondary , it will have a generated primary constructor with no arguments.

The visibility of the constructor will be public. How constructors are different from a normal member function? It must be placed in public section of class. Suppose you went to a shop to buy a marker. When you want to buy a marker, what are the options? The first one you go to a shop and say give me a marker. So when we said just I want a marker so whatever the frequently sold marker is there in the market or in his shop he will simply hand over that.

And this is what a default constructor is! The second method you go to a shop and say I want a marker a red in color and XYZ brand. So you are mentioning this and he will give you that marker. So in this case you have given the parameters.

And this is what a parameterized constructor is! Then the third one you go to a shop and say I want a marker like this a physical marker on your hand. So the shopkeeper will see that marker. A default constructor is the specific no-args constructor that is generated if no constructors are declared in a class. Similarily, you don't see the converse that no-args constructor is default constructor. Your second statement is what I tried to put. You said - "default constructor is also called no-arg constructor If that is not what you meant to your answer to mean, then you should correct it.

Thanks for your comment. I don't mean that. Now edited. Your updated version is still incorrect. The word "invoke" is about when a constructor is used Not just constructors with parameters. Again: I don't know if you really know these things or not. But what you are saying i. Show 2 more comments. Purpose of adding default constructor: Constructor's duty is to initialize instance variables, if there are no instance variables you could choose to remove constructor from your class. Constructor duty is to initialize memory space, in which the object is created.

The object initialization is Java Virtual Machine responsibility. StephenC not according to this article — MaxZoom. MaxZoom - You misunderstood the article I think. It says this: "To guard against such a scenario, Java makes certain that memory is initialized, at least to predictable default values, before it is used by any code.

And the "any code" includes the code of the constructor. Besides, if you want a reliable source, read what the JLS specifies.

And as there is no much code in a default constructor, it is the only player in doing so. I understand the article correctly. As JLS does not provide much explanation about default constructor, I would appreciate some reliable source of information to support your point.

But here's the problem. Show 1 more comment. Java Java 1, 1 1 gold badge 8 8 silver badges 20 20 bronze badges. Vogel 5, 5 5 gold badges 49 49 silver badges 70 70 bronze badges. This is wrong, this is a non-arg constructor, not a default constructor. Please refer below link for more details.

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