Subtyping

A value of a subtype can be substituted for a value of a supertype.

Related concepts:  TypePolymorphismInheritance

Closest Wikipedia entry:  Subtyping — In programming language theory, subtyping (also subtype polymorphism or inclusion polymorphism) is a form of type polymorphism in which a subtype is a datatype that is related to another datatype (the supertype) by some notion of substitutability, meaning that program elements, typically subroutines or functions, written to operate on elements of the supertype can also operate on elements of the subtype. If S is a subtype of T, the subtyping relation is often written S <: T, to mean that any term of type S can be safely used in a context where a term of type T is expected. The precise semantics of subtyping crucially depends on the particulars of what "safely used in a context where" means in a given programming language.

Misconceptions about Subtyping

11 documented Misconceptions

CallNotStaticallyChecked — Java

One can invoke a method on a reference of a class that does not have that method

ConcreteClassOnlyImplementClassAbstract — Java

A concrete class only needs to implement those abstract methods it inherits from abstract superclasses

ConcreteClassOnlyImplementDirectAbstract — Java

A concrete class only needs to implement abstract methods declared in its direct supertypes

ConcreteClassOnlyImplementInterfaceAbstract — Java

A concrete class only needs to implement those abstract methods it inherits from interfaces

ExceptionRoot — Java

Exception is the top-most exception class

InterfaceExtendClass — Java

An interface can extend a class

MultipleSuperclasses — Java

A class can have multiple superclasses

RuntimeExceptionChecked — Java

RuntimeExceptions are checked exceptions

StaticDispatch — Java

The method to be called is determined by the static type

SubtypeCompatibleWithSupertype — Java

A variable of a subtype can reference an object of a supertype

SupertypeIncompatibleWithSubtype — Java

A variable of a supertype cannot reference an object of a subtype