Java Constructors || Tutorials #36 смотреть онлайн

Java Constructors:
A constructor is a method that is automatically called when an object is
Initializing an Object with a Constructor created.
A constructor is a method that is automatically called when an instance of a class is created. Constructors normally perform initialization or setup operations, such as storing initial values in instance fields. They are called “constructors” because they help construct an object.
A constructor method has the same name as the class.

Notice that the constructor’s header doesn’t specify a return type—not even void. This is because constructors are not executed by explicit method calls and cannot return a value.

The method header for a constructor takes the following general format:
AccessSpecifier ClassName(Parameters...)

The Default constructor:
When an object is created, its constructor is always called. But what if we do not write a constructor in the object’s class? If you do not write a constructor in a class, Java automatically provides one when the class is compiled. The constructor that Java provides is known as the default constructor. The default constructor doesn’t accept arguments. It sets all of the object’s numeric fields to 0 and boolean fields to false. If the object has any fields that are reference variables, the default constructor sets them to the special value null, which means that they do not reference anything.
The only time that Java provides a default constructor is when you do not write your own constructor for a class.


No-Arg constructor:
A constructor that does not accept arguments is known as a no-arg constructor. The default constructor doesn’t accept arguments, so it is considered a no-arg constructor. In addition, you can write your own no-arg constructor.