is it possible to pass the type of an interface with generics? The interface: public interface AsyncCallback<T> In my test method: Mockito.any(AsyncCallback.class) Putting <ResponseX> behind or for .class didnt work. 8 Answers 8
Say you need to have a list/array of integers which you need iterate frequently, and I mean extremely often. The reasons may vary, but say it’s in the heart of the inner most loop of a high volume processing. In general, one would opt for using Lists (List) due to their flexibility in size. On … Read more
Typically, I’ve seen people use the class literal like this: Class<Foo> cls = Foo.class; But what if the type is generic, e.g. List? This works fine, but has a warning since List should be parameterized: Class<List> cls = List.class So why not add a <?>? Well, this causes a type mismatch error: Class<List<?>> cls = … Read more
Given the following example (using JUnit with Hamcrest matchers): Map<String, Class<? extends Serializable>> expected = null; Map<String, Class<java.util.Date>> result = null; assertThat(result, is(expected)); This does not compile with the JUnit assertThat method signature of: public static <T> void assertThat(T actual, Matcher<T> matcher) The compiler error message is: Error:Error:line (102)cannot find symbol method assertThat(java.util.Map<java.lang.String,java.lang.Class<java.util.Date>>, org.hamcrest.Matcher<java.util.Map<java.lang.String,java.lang.Class <? … Read more
What is the difference between <out T> and <T>? For example: public interface IExample<out T> { … } vs. public interface IExample<T> { … } 5 Answers 5
I’ve got a generic dictionary Dictionary<string, T> that I would like to essentially make a Clone() of ..any suggestions. 14 Answers 14
This question already has answers here: Generic list type with question mark [duplicate] (5 answers) Closed 11 months ago. This is a small snippet of code taken from some of the examples that accompany the Stanford Parser. I’ve been developing in Java for about 4 years, but have never had a very strong understanding of … Read more
I have a foreach loop reading a list of objects of one type and producing a list of objects of a different type. I was told that a lambda expression can achieve the same result. var origList = List<OrigType>(); // assume populated var targetList = List<TargetType>(); foreach(OrigType a in origList) { targetList.Add(new TargetType() {SomeValue = … Read more
I was reading A Tour of Scala: Abstract Types. When is it better to use abstract types? For example, abstract class Buffer { type T val element: T } rather that generics, for example, abstract class Buffer[T] { val element: T } 4 Answers 4
I have a class that I want to use to store “properties” for another class. These properties simply have a name and a value. Ideally, what I would like is to be able to add typed properties, so that the “value” returned is always of the type that I want it to be. The type … Read more
