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java Programming Glossary: covariantwhy polymorphism doesn't treat generic collections and plain arrays the same way? http://stackoverflow.com/questions/10770585/why-polymorphism-doesnt-treat-generic-collections-and-plain-arrays-the-same-way An Arrays Example With arrays you can do this arrays are covariant as others have explained Integer myInts 1 2 3 4 Number myNumber.. right However you are not allowed to put anything into a covariant structure. myNumst.add 45L compiler error This would not be..
Covariance and contravariance in programming languages http://stackoverflow.com/questions/1163465/covariance-and-contravariance-in-programming-languages contains elements of type T for some T . List would be covariant if S is a subtype of T iff List S is a subtype of List T Where..
Strange Java null behavior in Method Overloading [duplicate] http://stackoverflow.com/questions/14789478/strange-java-null-behavior-in-method-overloading
http://stackoverflow.com/questions/1817524/generic-arrays-in-java create an array of your parameterized type. Arrays are covariant . That means they retain the type of their elements at runtime... type No because it is not type safe. Arrays are covariant which means that an array of supertype references is a supertype..
What's the issue with creating a generic array? [duplicate] http://stackoverflow.com/questions/18581002/whats-the-issue-with-creating-a-generic-array differences working with arrays and generics. Arrays are covariant Generics are not What that means You must be knowing by now..
Demonstrate covariance and contravariance in Java? http://stackoverflow.com/questions/2501023/demonstrate-covariance-and-contravariance-in-java Sub extends Super String getSomething Sub#getSomething is covariant because it returns a subclass of the return type of Super#getSomething.. for Generics List String aList... List extends Object covariantList aList List super String contravariantList aList You can.. contravariantList aList You can now access all methods of covariantList that doesn't take a generic parameter as it must be something..
http://stackoverflow.com/questions/2660827/java-generics-covariance java library j jtp01255.html Under Generics are not covariant the author states Because ln is a List adding a Float to it.. is a list of integers which is why generic types cannot be covariant. I can't understand the part where it says if ln were aliased.. a float is not an integer. Conclusion Generics are not covariant. Note I recommend you read Effective Java 2nd Edition Chapter..
What is the difference between <E extends Number> and <Number>? http://stackoverflow.com/questions/2770264/what-is-the-difference-between-e-extends-number-and-number doesn't. Generics in Java are invariant. They're not covariant like arrays. That is in Java Double is a subtype of Number but..
what java.lang.reflect.Method.isBridge () used for? http://stackoverflow.com/questions/289731/what-java-lang-reflect-method-isbridge-used-for in the comment bridge methods are also needed for covariant overriding In Java 1.4 and earlier one method can override another..
Why in java enum is declared as Enum<E extends Enum<E>> [duplicate] http://stackoverflow.com/questions/3061759/why-in-java-enum-is-declared-as-enume-extends-enume it's defined to return a value of type Object . Thanks to covariant return types specific subclasses can and often do define that..
Java generics and array initialization http://stackoverflow.com/questions/470198/java-generics-and-array-initialization generic arrays is this one arguing that since arrays are covariant and generics are not you could subvert the generic typing if..
Most efficient way to cast List<SubClass> to List<BaseClass> http://stackoverflow.com/questions/5082044/most-efficient-way-to-cast-listsubclass-to-listbaseclass do not behave the same as arrays in Java. Arrays are covariant that is it is allowed to do this SubClass subs ... BaseClass..
What is the difference between ? and Object in Java generics? http://stackoverflow.com/questions/678822/what-is-the-difference-between-and-object-in-java-generics why generics and arrays don't mix well. arrays in Java are covariant generics are not they are invariant . Sample If you'd like to..
Java Generic List<List<? extends Number>> http://stackoverflow.com/questions/746089/java-generic-listlist-extends-number not also a List of Vehicles . We say that List Car is not covariant with List Vehicle . Java requires you to explicitly tell it.. will tell Java that this combined type should also be covariant List extends List extends Number l new ArrayList List Number..
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