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We cannot instantiate an inner class within a static context of the outer class, but when we declare this inner class as package- private. we are able to access its constructor. But how ? what is the ...

Any C++ class can be first forward declared, and defined only later in the program. Are function-local classes an exception from this rule? Please consider a simplified program: auto f() { struct ...

Can nested classes or anonymous classes extend a class or implement an interface in Java? If so, are there any limitations or things I should be aware of? I'm not very familiar with nested classes, ...

Say, I have an abstract superclass and an abstract test class for testing subclasses. abstract class Superclass { } @RequiredArgsConstructor abstract class SuperclassTest<T extends Superclass> {...

I find an "Argument type mismatch" error in multiply function and don't know how to fix it. The code is: abstract class Semigroup<T1> { abstract val one: SemigroupElement<T1> ...

suppose I have a template class template<typename T> struct Foo { struct Bar; }; specializing Foo<int>::Bar template<> struct Foo<int>::Bar { struct Private; // I ...

Java shouldn't allow static methods within an inner class and yet this code compiles and runs. How is this possible? class Test{ static int j=20; public void m1() { class Inner{ ...

I am very curious about this question. The Java Language Specification has told me part of the reason： In a class instance creation expression for a non-private inner member class, §15.9.2 specifies ...