Difference between Singleton class and static class in SAP ABAP

A static class can only have static members — you cannot declare instance members (methods, variables, properties, etc.) in a static class. You can have a static constructor in a static class but you cannot have an instance constructor inside a static class.

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.

That constructor will be called as an overloaded constructor. Overloading is also another form of polymorphism in Java which allows having multiple constructors with a different name in one Class in java.

A specific class can have only one static constructor. It does not allow inheritance or overloading . It is invoked automatically, can not be called directly or explicitly. If the value of static fields is not initialized, it will initialize to default values.