static nested class
Nested classes that are static are called static nested classes. Nested class in different programming languages: * Classes in C++ are merely nested type definitions, so only act as namespaces for nested type definitions. Nested class in C++ is essential static. * Nested class in C# is static. * In Kotlin, nested class is static by default; but we can use inner keyword to create an inner class in Kotlin. * PHP, JavaScript, and TypeScript has no nested class, so also has no static nested class.