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Why can't I modify class member variable outside any methods? [duplicate]

由 懵懂的女人 提交于 2020-01-22 03:44:05
问题 This question already has answers here : Syntax error on token(s) “product1. ”VariableDeclaratorId expected after this token (1 answer) syntax error on tokens, variableDeclarator expected instead (3 answers) syntax error on addActionListener (3 answers) I have an error with system.out.print and I don't know why? [closed] (7 answers) Syntax error on token(s), misplaced construct(s) (4 answers) Closed 2 years ago . I have a class with some variables. When I instantiate an object of that class

Is `this` keyword optional when accessing members in C#?

由 。_饼干妹妹 提交于 2020-01-21 11:01:34
问题 I notice that if you have a private member in a class, you can access it in the class methods by just referring to it's name. You do not need to say this.memberName , just memberName works. So is the this keyword optional in the context of member access? I do see it is useful when you want to clarify the scope - when you have 2 variables with the same name. Is there any other reason to use it when accessing members? 回答1: Yes, it's optional. The only times you'd have to use it are when you

Is `this` keyword optional when accessing members in C#?

由 妖精的绣舞 提交于 2020-01-21 11:01:07
问题 I notice that if you have a private member in a class, you can access it in the class methods by just referring to it's name. You do not need to say this.memberName , just memberName works. So is the this keyword optional in the context of member access? I do see it is useful when you want to clarify the scope - when you have 2 variables with the same name. Is there any other reason to use it when accessing members? 回答1: Yes, it's optional. The only times you'd have to use it are when you

C++ class member check if not a template

由 一世执手 提交于 2020-01-15 11:14:54
问题 template instantiation check for member existing in class explains how to check if a class member exists in a template. However, given a set of processes within a switch ( NOT a template) is there a way to handle a member check case. It should be similar to something like this. Note that the actual class definition is not under my control and is being created in a future release of header files and libraries that I am using. I am aware that this preprocessor example would not work, but since

public interface member in c#8

由 限于喜欢 提交于 2020-01-15 03:10:51
问题 Since the latest version of c#, it is possible to write the following interface: public interface IMyInterface { public void MyMethod(); } This seems like a code smell to me, as I feel like the intention was to write the previously available: public interface IMyInterface { void MyMethod(); } Are those two interfaces exactly the same ? Does the public keyword add/changes anything ? Is this something that should be corrected, or am I wrong and should public be consistently used now ? 回答1:

method overriding Vs class variable overriding in java

由 ℡╲_俬逩灬. 提交于 2020-01-14 19:53:27
问题 I was just trying some sample code for checking class variable overriding behavior in Java. Below is the code: class A{ int i=0; void sayHi(){ System.out.println("Hi From A"); } } class B extends A{ int i=2; void sayHi(){ System.out.println("Hi From B"); } } public class HelloWorld { public static void main(String[] args) { A a= new B(); System.out.println("i->"+a.i); // this prints 0, which is from A System.out.println("i->"+((B)a).i); // this prints 2, which is from B a.sayHi(); // method

enum constructors (creating members of members)

由 人走茶凉 提交于 2020-01-14 14:40:48
问题 In D, I'm trying to create an enum whose members have members. I can better explain what I'm trying to do with an example, where s and i stand in for the sub-members I'm trying to create: In Python, I can do this: class Foo(enum.Enum): A = "A string", 0 B = "B string", 1 C = "C string", 2 def __init__(self, s, i): self.s = s self.i = i print(Foo.A.s) Java can do something like this: public enum Foo { A("A string", 0), B("B string", 1), C("C string", 2); private final String s; private final

SpringMVC+redis整合

由 为君一笑 提交于 2020-01-14 06:55:22
转载：http://www.cnblogs.com/wuxinliulei/p/5216712.html http://www.tuicool.com/articles/7Bni6f 在网络上有一个很多人转载的springmvc+redis整合的案例，不过一直不完整，也是被各种人装来转去，现在基本将该框架搭建起来。 1 2 3 4 5 6 7 package com.pudp.bae.base; import java.io.Serializable; public abstract class BaseModel implements Serializable{ } 　　 1 2 3 4 5 6 7 8 9 10 11 12 13 package com.pudp.bae.base; import java.util.Map; import org.springframework.web.servlet.ModelAndView; public class BaseMultiController { protected ModelAndView toView( final String url, final Map<String,Object> map) { ModelAndView view = new ModelAndView(url); return view; } } 1

Fatal error: Call to a member function getKeyName()

由 一世执手 提交于 2020-01-13 08:37:38
问题 I am new in joomla . i have created a joomla component and when i click on new button in admin then i am getting such error. Fatal error: Call to a member function getKeyName() on a non-object in C:\xampp\htdocs\Joomla1\libraries\joomla\application\component\modeladmin.php on line 801 Please help 回答1: The problem is cause by your JTable class. Make sure you have correct filename and class name in administrator/components/com_YOUREXTENSION/tables/ You can find example in any core Joomla

_beginthreadex static member function

由 本秂侑毒 提交于 2020-01-11 12:05:15
问题 How do I create a thread routine of a static member function class Blah { static void WINAPI Start(); }; // .. // ... // .... hThread = (HANDLE)_beginthreadex(NULL, 0, CBlah::Start, NULL, NULL, NULL); This gives me the following error: ***error C2664: '_beginthreadex' : cannot convert parameter 3 from 'void (void)' to 'unsigned int (__stdcall *)(void *)'*** What am I doing wrong? 回答1: Sometimes, it is useful to read the error you're getting. cannot convert parameter 3 from 'void (void)' to
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