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问题 I am not sure what this means, whenever before you write a code, people say this public static void main(String[] args) { What does that mean? 回答1: Here is a little bit detailed explanation on why main method is declared as public static void main(String[] args) Main method is the entry point of a Java program for the Java Virtual Machine(JVM). Let's say we have a class called Sample class Sample { static void fun() { System.out.println("Hello"); } } class Test { public static void main

问题 If B inherits from A using public , can B override one of the functions and force it to be private? class A { public: virtual double my_func1(int i); virtual double my_func2(int i); } class B : public A // Notice the public inheritance { public: virtual double my_func1(int i); private: virtual double my_func2(int i); } How about the other way around? if the inheritance type is private - can B force a specific function to be public? What if A is pure abstract? does it make a difference? Would

问题 Given the Java code below, what\'s the closest you could represent these two static final variables in a Ruby class? And, is it possible in Ruby to distinguish between private static and public static variables as there is in Java? public class DeviceController { ... private static final Device myPrivateDevice = Device.getDevice(\"mydevice\"); public static final Device myPublicDevice = Device.getDevice(\"mydevice\"); ... public static void main(String args[]) { ... } } 回答1: There really is

问题 Seems like every C# static analyzer wants to complain when it sees a public field. But why? Surely there are cases where a public (or internal) field is enough, and there is no point in having a property with its get_ and set_ methods? What if I know for sure that I won\'t be redefining the field or adding to it (side effects are bad, right?) - shouldn\'t a simple field suffice? 回答1: Because it breaks encapsulation -- this is why most people use accessors heavily. However, if you think it's

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Why use getters and setters? Is there any advantage to making methods to access private variables in your class instead of making the variable public? For example is the second case better than the first? //Case 1 public class Shoe{ public int size; } //Case 2 public class Shoe{ private int size; public int getSize(){ return size; } public void setSize(int sz){ size = sz; } } 回答1: What I have seen someday on SO,

问题 When and why should I use public , private , and protected functions and variables inside a class? What is the difference between them? Examples: // Public public $variable; public function doSomething() { // ... } // Private private $variable; private function doSomething() { // ... } // Protected protected $variable; protected function doSomething() { // ... } 回答1: You use: public scope to make that property/method available from anywhere, other classes and instances of the object. private

问题 In Java, are there clear rules on when to use each of access modifiers, namely the default (package private), public , protected and private , while making class and interface and dealing with inheritance? 回答1: The official tutorial may be of some use to you. ______________________________________________________________ | │ Class │ Package │ Subclass │ Subclass │ World | | │ │ │(same pkg)│(diff pkg)│ | |───────────┼───────┼─────────┼──────────┼──────────┼────────| |public │ + │ + │ + │ + │ +