scope

问题 This will compile class X { public static void main(String args[]) { { int a = 2; } { int a = 3; } } } This won't class X { public static void main(String args[]) { int a = 2; { int a = 3; } } } I expected both to compile (maybe it is the way C works?). What is the reason because it is not possible to declare a variable in a block with the same name of one in the outer block? 回答1: The short answer is: Because this is the way the Java language is defined in JLS §6.4. You might be used from

问题 can anyone tell me how to create a list in one class and access it from another? 回答1: public class MyClass { private List<string> myList = new List<string>(); public List<string> GetList() { return myList; } } You can have any anything there instead of string. Now you can make an object of MyClass and can access the public method where you have implemented to return myList . public class CallingClass { MyClass myClass = new MyClass(); public void GetList() { List<string> calledList = myClass

问题 How can I get the value of userId passed to this method in my anonymous inner subclass here? public void doStuff(String userID) { doOtherStuff(userID, new SuccessDelegate() { @Override public void onSuccess() { Log.e(TAG, "Called delegate!!!! "+ userID); } }); } I get this error: Cannot refer to a non-final variable userID inside an inner class defined in a different method I'm pretty sure I can't assign it as final since it's a variable with an unknown value. I had heard that this syntax

问题 This question already has answers here : How to print value of global variable and local variable having same name? (4 answers) Closed 2 years ago . for example #include<stdio.h> int foo = 100; int bar() { int foo; /* local foo = global foo, how to implemented? */ return 0; } int main() { int result = bar(); return 0; } I think in the function bar, calling foo directly will just get the global foo. How can I refer the local foo? I know in C++, there is this pointer. However, does C has

问题 Typically the 'using' declaration is used to bring into scope some member functions of base classes that would otherwise be hidden. From that point of view it is only a mechanism for making accessible information more convenient to use. However: the 'using' declaration can also be used to change access constraints (not only for functions but also for attributes). For example: class C{ public: int a; void g(){ cout << "C:g()\n"; } C() : a(0){} }; class D : public C{ private: using C::a; using

问题 I have a superclass and a subclass, both of which define instance variables. Rough outline of superclass: /* GenericClass.h */ @interface GenericClass : NSObject { /* some variables */ } @end /* GenericClass.m */ @implementation GenericClass /* ... */ @end Outline of subclass: /* SpecificClass.h */ #import "GenericClass.h" @interface SpecificClass : GenericClass { NSMutableString *str; } /* SpecificClass.m */ #import "SpecificClass.h" @implementation SpecificClass - (void)aMethod { //Debugger

问题 function Foo(f) { var f = f; } Here inside the function, variable f is local to the Foo (it has a function scope), but why is the variable f in the argument list not in conflict? Maybe because it is bound inside the Foo.arguments object? In other languages we cannot declare an argument variable with the same name as a local variable. How is this name ambiguity resolved? Or, How do you reference each of the two distinct f variables later in the method? 回答1: JavaScript does a couple of things

问题 I'm writing Perl for quite some time now and always discovering new things, and I just ran into something interesting that I don't have the explanation to it, nor found it over the web. sub a { sub b { print "In B\n"; } } b(); how come I can call b() from outside its scope and it works? I know its a bad practice to do it, and I dont do it, I use closured and such for these cases, but just saw that. 回答1: Subroutines are stored in a global namespace at compile time. In your example b(); is

问题 Look at this Fiddle, what do I have to change, that the expressions in the template get evaluated using the arguments I defined in the HTML? The SAVE-button should call the blabla() -function of the controller, since I pass it? var myApp = angular.module('MyApp',[]) myApp.directive('editkeyvalue', function() { return { restrict: 'E', replace: true, scope: { accept: "expression" }, template : '<div><label class="control-label">{{key}}</label>' + '<label class="control-label">{{key}}</label>' +

问题 I am a C# developer experimenting with JavaScript and I'm trying to get my head around the scope :) I have the following code which contains an addEventListener in which I want to use a field from my object: (function(window) { function Keyboard() { this.keys = {}; } Keyboard.prototype.handle_keydown = function(args) { this.keys[args.keyCode] = true; } Keyboard.prototype.listen = function() { window.addEventListener('keydown', this.handle_keydown); } app.util.keyboard = new Keyboard(); })