Wednesday, March 30, 2022
Constructor in Java
Constructor
- A special method that matches the name of the class and has no return type
- Constructors are executed when a new instance of the class is created (
new Main()
). This process is called instantiation, because it creates a new instance of the class. - The method name and the class name should be exactly same (note that Java is case sensitive)
Constructors can include parameters, like arrays, primitive types or generics. But cannot include var. The below constructor will not compile.
class Main { public Main( var number ) { } }
- There can be multiple constructors in a class, provided that the constructor parameters are distinct.
- Declaring multiple constructors with different signatures is reffered to as constructor overloading.
- Every class in Java will have a constructor. If you didn't code it Java will include the default no-argument constructor automatically during compilation process.
Private Constructor is a special constructor which is declared as private. Having private constructors prevents other classes from the class. It is generally used when the class has only static methods.
class Main { private Main() { } }
- Classes with a private constructor can be extended only by an inner class, because an inner class is the only one that can access a private constructor by calling super().
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