static-methods

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 6 years ago . Both Class and Namespace? This question is about a pattern that I am seeing myself use more and more: Having both a class and a

问题 Why are static methods supported from Java 8? What is the difference between the two lines in main method in below code? package sample; public class A { public static void doSomething() { System.out.println("Make A do something!"); } } public interface I { public static void doSomething() { System.out.println("Make I do something!"); } } public class B { public static void main(String[] args) { A.doSomething(); //difference between this I.doSomething(); //and this } } As we can see above, I

问题 Per MSDN: A static constructor does not take access modifiers or have parameters. A static constructor is called automatically to initialize the class before the first instance is created or any static members are referenced. A static constructor cannot be called directly. Can any one please explain why can't the static constructor have parameters? 回答1: As MSDN says, A static constructor is called automatically to initialize the class before the first instance is created . Therefore you can't

问题 This question already has answers here : Java - No enclosing instance of type Foo is accessible (5 answers) Closed 6 years ago . The whole code is: public class ThreadLocalTest { ThreadLocal<Integer> globalint = new ThreadLocal<Integer>(){ @Override protected Integer initialValue() { return new Integer(0); } }; public class MyThread implements Runnable{ Integer myi; ThreadLocalTest mytest; public MyThread(Integer i, ThreadLocalTest test) { myi = i; mytest = test; } @Override public void run()

问题 In swift, an instance func can't call a static/class func without prefixing the method call with the class name. OR you can use type(of: self) , e.g class Foo { static func doIt() { } func callIt() { Foo.doIt() // This works type(of: self).doIt() // Or this doIt() // This doesn't compile (unresolved identifier) } } My question is, what's the difference here? Is it just a matter of coding style, or is there some difference e.g. static or dynamic dispatch going on? If it is just coding style,

问题 In swift, an instance func can't call a static/class func without prefixing the method call with the class name. OR you can use type(of: self) , e.g class Foo { static func doIt() { } func callIt() { Foo.doIt() // This works type(of: self).doIt() // Or this doIt() // This doesn't compile (unresolved identifier) } } My question is, what's the difference here? Is it just a matter of coding style, or is there some difference e.g. static or dynamic dispatch going on? If it is just coding style,

问题 In PHP laravel, we have codes like $user = User::find(1); var_dump($user->name); I am not concerning how to use the find method, I am concerning why laravel use a static method? Shouldn't the use of static method make the method hard to test? Will it be better if they designed using singleton? e.g. $user = User::getInstance()->find(1); var_dump($user->name); 回答1: In fact, your example is very similar to what Laravel does behind the scene. When you do User::find() , you are actually asking for

问题 I am getting an error code in the result. code below. I am basically trying to get a data set from SingleColumn method and use it in SMA method. But I am getting results deos not exist in current context. static public void SMA() { double[] closePrice = results.ToArray(); Below you can see the SingleColumn and part of SMA code. #region Single Column //static public double results; static public void SingleColumn(IEnumerable<string> strs, int highNum) { #region spilt data to columns Console

问题 When i was going through Singleton design pattern in Objective C, I found lot of people using the below code to create it. @interface Base : NSObject {} +(id)instance; @end @implementation Base +(id) instance { static id theInstance = nil; if (theInstance == nil) { theInstance = [[self alloc] init]; } return theInstance; } @end Here i did not get the why do we have to assign the static variable to nil in a method instead it can be declared outside the method and assigned to nil. Because

问题 Simmilar question (related with Python2: Python: check if method is static) Lets concider following class definition: class A: def f(self): return 'this is f' @staticmethod def g(): return 'this is g' In Python 3 there is no instancemethod anymore, everything is function, so the answer related to Python 2 will not work anymore. As I told, everything is function, so we can call A.f(0) , but of course we cannot call A.f() (argument missmatch). But if we make an instance a=A() and we call a.f()