Contents
Which method return type returns a value apex?
There are two modifiers for Class Methods in Apex – Public or Protected. Return type is mandatory for method and if method is not returning anything then you must mention void as the return type. Additionally, Body is also required for method.
Can overriding methods have different return types?
Yes. It is possible for overridden methods to have different return type . But the limitations are that the overridden method must have a return type that is more specific type of the return type of the actual method.
Which is a covariant return type?
In object-oriented programming, a covariant return type of a method is one that can be replaced by a “narrower” type when the method is overridden in a subclass. This usually implies that the return types of the overriding methods will be subtypes of the return type of the overridden method.
What is covariant return type example?
Simple example of Covariant Return Type As you can see in the above example, the return type of the get() method of A class is A but the return type of the get() method of B class is B. Both methods have different return type but it is method overriding. This is known as covariant return type.
What are the requirements for covariant return types?
The override method must have a return type that is convertible by an identity conversion or (if the method has a value return – not a ref return) implicit reference conversion to the return type of the overridden base method. And the following additional requirements are appended to that list:
When is a covariant return type compile time error?
If the invocation is of an instance method, and the receiver is of an interface type T, the associated type is picked from the declaration or override of the method found in the most derived interface from among T and its direct and indirect base interfaces. It is a compile-time error if no unique such type exists.
Is it valid to return null account in apex?
Null can be any type. So returning a Null Account is perfectly valid. You never need to declare that an Account will return an Account OR Null (and this is not possible) because every complex and primative data type can be Null. If you declare a variable and don’t initialize it with a value, it will be null.
When to use override declarations in return types?
Override declarations appearing in more derived types would be required to provide a return type at least as specific as that appearing in overrides in its base types. Callers of the method or property would statically receive the more refined return type from an invocation.