Lower Bounds

Java-Lower Bounds

Lower Bounds Wildcard instantiations actually allow another type of bound called a lower bound as well. A lower bound is specified with the keyword super and requires that instantiations be of a certain type or any of its supertypes, up to upper bound of Type variable or Object. Consider the following classes and statement : The … Read more…

Implementing the Raw Type of Generic Interface

Java-Implementing the Raw Type for the Generic Interface

Implementing the Raw Type for the Generic Interface Every generic interface has a raw type. When you implement an generic interface in an ordinary class without specifying a type argument, your class is implementing the raw type, so the methods in the interface are declared with parameters and/or return types of type Object. For example … Read more…

Ambiguity Errors in Generics

Java-Ambiguity Errors in Generics

Ambiguity Errors in Generics The inclusion of generics gives rise to another type of error that you must guard against: ambiguity. Ambiguity errors occur when erasure causes two seemingly distinct generic declarations to resolve to the same erased type, causing a conflict. Following is an example that involves method overloading : Gen declares two generic … Read more…

Java-Generic Constructors

Generic Constructors It is possible for constructors to be generic, even if their class is not. For example, in the following program, NumberToInt constructor specifies a parameter of a generic type, which must be a subclass of Number, NumberToInt constructor can be called with any numeric type, including Integer, Float, or Double. Therefore, even though … Read more…

Generic Interfaces

Java-Generic Interfaces

Generic Interfaces Generics also work with interfaces. Thus, you can also have generic interfaces. Generic interfaces are specified just like generic classes. For example : The MyInterface is a generic interface that declares the method called myMethod( ). In general, a generic interface is declared in the same way as is a generic class. In this case, the … Read more…

Bridge Method

Java-Bridge Method

Bridge Method Sometimes, the compiler will need to add a bridge method to a class to handle situations in which the type erasure of an overriding method in a subclass does not produce the same erasure as the method in the superclass. In this case, a method is generated that uses the type erasure of … Read more…