Consider the following: public class Foo { static class A { public static void doThing() { System.out.println(“the thing”); } } static class B extends A { } static class C extends B { public static void doThing() { System.out.println(“other thing”); } } public static void main(String[] args) { A.doThing(); B.doThing(); C.doThing(); } } Run it! … Read more
This is deliberate. Static classes try to prevent inappropriate use, so in almost all situations, you can’t use them in situations where you’d normally want an instance of the type… and that includes type arguments. See section “Static classes” of the C# 6 spec for the very limited set of situations in which you can … Read more
It’s a rule of the language, known as the One Definition Rule. Within a program, each static object (if it’s used) must be defined once, and only once. Class definitions typically go in header files, included in multiple translation units (i.e. from multiple source files). If the static object’s declaration in the header were a … Read more
Well sure! Let’s assume that you have in interface IMyCollection. It has a method boolean isMutable(). Now you have two classes, class MyMutableList and class MyImmutableList, which both implement IMyCollection. Each of them would override the instance method isMutable(), with MyMutableList simply returning true and MyImmutableList returning false. isMutable() in both classes is an instance … Read more
To get the equivalent of a static constructor, you need to write a separate ordinary class to hold the static data and then make a static instance of that ordinary class. class StaticStuff { std::vector<char> letters_; public: StaticStuff() { for (char c=”a”; c <= ‘z’; c++) letters_.push_back(c); } // provide some way to get at … Read more
Addition of static methods in interface in Java 8 came with 1 restriction – those methods cannot be inherited by the class implementing it. And that makes sense, as a class can implement multiple interface. And if 2 interfaces have same static method, they both would be inherited, and compiler wouldn’t know which one to … Read more
Each thread has its own stack space, each time a thread calls a method (static or virtual) that call allocates a stack frame, which holds local variables. nothing about this is specific to static methods. Static methods can be called concurrently by multiple threads, unless you specifically do something to thwart that, such as requiring … Read more
You should store them externally on a service like S3 – while Heroku can serve static files, it’s not designed to. Here’s a good primer on getting started with S3: https://devcenter.heroku.com/articles/s3 Use django-storages http://django-storages.readthedocs.org/en/latest/index.html to collect static files to your S3 bucket and serve them accordingly. These are the necessary settings you’ll need to have … Read more
When talking about non-local static objects there are not many guarantees. As you already know (and it’s also been mentioned here), it should not write code that depends on that. The static initialization order fiasco… Static objects goes through a two-phase initialization: static initialization and dynamic initialization. The former happens first and performs zero-initialization or … Read more