class

Dynamic loading a class in java with a different package name

由 邮差的信 提交于 2020-01-10 10:28:49
问题 Is it possible to load a class in Java and 'fake' the package name/canonical name of a class? I tried doing this, the obvious way, but I get a "class name doesn't match" message in a ClassDefNotFoundException . The reason I'm doing this is I'm trying to load an API that was written in the default package so that I can use it directly without using reflection. The code will compile against the class in a folder structure representing the package and a package name import. ie: ./com

JAVA CLASS类的初步认识与基本用法

由 僤鯓⒐⒋嵵緔 提交于 2020-01-10 10:28:45
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 首先咱们先来说下这个类在JAVA里充当类什么角色： 首先这个类跟Objct是没关系的，但是他的对象却全部有关系； 相当于玩游戏里的外挂 相当于打外国游戏时你买的代理 相当于你美国的特工 以上这几个比较适用初学者初步对CLASS这个类的理解 总之这个类就是充当强盗的角色，强取豪夺别人东西； 接下来写个例子，结合我这几句解释相信每个初学者就能知道到底什么是CLASS了 package exp class A{ private int i=0; private A(int i){ this.i=i; } private void f(){ System.out.print(i+""); } } 像上面写的这个类，要是在我们以前，除非用单实例模式来使用它，也就是在写的时候要主动添加几个方法进去让别人去使用它，不然就没法使用了； 但是有了CLASS这个强盗之后，妈妈再也不用担心我使用不了那个类了。 记得用全部私有的类来测试自己，就像我上面写的一样，像其他人写公有的来测试有时候会错得自己都不知道已经错了 接下来一起看看怎么用CLASS来使用吧： 下面是几个最基本的用法 public class B{ public static void main (String[] args){ Class cl=Class

Calling GSL function inside a class in a shared library

由 谁都会走 提交于 2020-01-10 04:43:06
问题 I'm trying make a shared library in c++ implementing tools for Fermi gases. I'm using the GSL library to solve a function numerically and my code runs without a problem without when running as a script, but when trying to convert it to a shared library and classes I encounter problems. I've seen similar questions: Q1 Q2 Q3 I'm fairly new to c++-programming and cannot seem to adapt the different answers to my problem. Probably since I do not quite understand the answers. My code is: /* Define

Global qualification in a class declarations class-head

由 那年仲夏 提交于 2020-01-10 04:25:20
问题 We found something similar to the following (don't ask ...): namespace N { struct A { struct B; }; } struct A { struct B; }; using namespace N; struct ::A::B {}; // <- point of interest Interestingly, this compiles fine with VS2005, icc 11.1 and Comeau (online), but fails with GCC: global qualification of class name is invalid before '{' token From C++03, Annex A, it seems to me like GCC is right: the class-head can consist of nested-name-specifier and identifier nested-name-specifier can't

How do you iterate through current class properties (not inherited from a parent or abstract class)?

由 自作多情 提交于 2020-01-10 04:12:44
问题 I know that PHP5 will let you iterate through a class's properties. However, if the class extends another class, then it will include all of those properties declared in the parent class as well. That's fine and all, no complaints. However, I always understood SELF as a pointer to the current class, while $this also points to the current object (including stuff inherited from a parent) Is there any way I can iterate ONLY through the current class's properties. Reason why I'm asking this.... I

Can't have a function as a class attribute in Python

由 纵然是瞬间 提交于 2020-01-10 03:45:08
问题 I want to have a plain old function as a class constant. However, Python "helpfully" turns it into a method for me: class C(object): a = 17 b = (lambda x : x+1) print C.a # Works fine for int attributes print C.b # Uh-oh... is a <unbound method C.<lambda>> now print C.b(1) # TypeError: unbound method <lambda>() must be called # with C instance as first argument (got int instance instead) Is there a way to prevent my function from becoming a method? In any case, what is the best "Pythonic"

Create an instance of a React class from a string

由 折月煮酒 提交于 2020-01-10 02:28:30
问题 I have a string which contains a name of the Class (this is coming from a json file). This string tells my Template Class which layout / template to use for the data (also in json). The issue is my layout is not displaying. Home.jsx: //a template or layout. var Home = React.createClass({ render () { return ( <div>Home layout</div> ) } }); Template.jsx: var Template = React.createClass({ render: function() { var Tag = this.props.template; //this is the name of the class eg. 'Home' return (

Java Double vs double: class type vs primitive type

由 只愿长相守 提交于 2020-01-09 13:52:08
问题 I was curious to what the performance differences between Java's class and primitive type for double were. So I created a little benchmark and found the class type to be 3x-7x slower than the primitive type. (3x on local machine OSX, 7x on ideone) Here is the test: class Main { public static void main(String args[]) { long bigDTime, littleDTime; { long start = System.nanoTime(); Double d = 0.0; for (Double i = 0.0; i < 1432143.341; i += 0.1) { d += i; } long end = System.nanoTime(); bigDTime

Java - The difference between class “ClassName” and public class “ClassName”

由 穿精又带淫゛_ 提交于 2020-01-09 12:41:52
问题 What's the difference between class x { //code here } and public class x { //code here } Sometimes I see examples on the Internet and they'll have public class instead of class and they're all simple programs. I use class for my assignments and so does everybody else 回答1: The first one will result in your class being assigned the default visibility, that is package-private (ie: accessible within the same package ). The second one makes it public , that is, visible to any other class.

Java - The difference between class “ClassName” and public class “ClassName”

由 眉间皱痕 提交于 2020-01-09 12:41:52
问题 What's the difference between class x { //code here } and public class x { //code here } Sometimes I see examples on the Internet and they'll have public class instead of class and they're all simple programs. I use class for my assignments and so does everybody else 回答1: The first one will result in your class being assigned the default visibility, that is package-private (ie: accessible within the same package ). The second one makes it public , that is, visible to any other class.
订阅 class