Try the `forName(String name, boolean initialize, ClassLoader loader)` method of `Class` and set the param `initialize` to `false`.

[JavaDoc link](http://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#forName(java.lang.String,%20boolean,%20java.lang.ClassLoader))

I&#39;ve noticed that both of these work the same:

`if x not in list` and `if not x in list`.

Is there some sort of difference between the two in certain cases? Is there a reason for having both, or is it just because it&#39;s more natural for some people to write one or the other?

Which one am I more likely to see in other people&#39;s code?


&quot;x not in&quot; vs. &quot;not x in&quot;

I&#39;m working with C#, Framework 3.5 (VS 2008).

I&#39;m using the `ConfigurationManager` to load a config (not the default app.config file) into a Configuration object.

Using the Configuration class, I was able to get a `ConfigurationSection`, but I could not find a way to get the values of that section.

In the config, the `ConfigurationSection` is of type `System.Configuration.NameValueSectionHandler`.


For what it worth, when I used the method `GetSection` of the `ConfigurationManager` (works only when it was on my default app.config file), I received an object type, that I could cast into collection of pairs of key-value, and I just received the value like a Dictionary. I could not do such cast when I received `ConfigurationSection` class from the Configuration class however.

EDIT:
Example of the config file:

    &lt;configuration&gt;
      &lt;configSections&gt;
        &lt;section name=&quot;MyParams&quot; 
                 type=&quot;System.Configuration.NameValueSectionHandler&quot; /&gt;
      &lt;/configSections&gt;
    
      &lt;MyParams&gt;
        &lt;add key=&quot;FirstParam&quot; value=&quot;One&quot;/&gt;
        &lt;add key=&quot;SecondParam&quot; value=&quot;Two&quot;/&gt;
      &lt;/MyParams&gt;
    &lt;/configuration&gt;



Example of the way i was able to use it when it was on app.config (the &quot;GetSection&quot; method is for the default app.config only):

    NameValueCollection myParamsCollection =
                 (NameValueCollection)ConfigurationManager.GetSection(&quot;MyParams&quot;);
    
    Console.WriteLine(myParamsCollection[&quot;FirstParam&quot;]);
    Console.WriteLine(myParamsCollection[&quot;SecondParam&quot;]);

How to get the values of a ConfigurationSection of type NameValueSectionHandler

If I use
 
       try {
          Class.forName(&quot;my.package.Foo&quot;);
          // it exists on the classpath
       } catch(ClassNotFoundException e) {
          // it does not exist on the classpath
       }

the static initializer block of &quot;Foo&quot; is kicked off. Is there a way to determine whether a class &quot;my.package.Foo&quot; is on the classpath without kicking off its static initializer?

Check if class exists in Java classpath without running its static initializer?

If I use
<pre><code class="hljs language-csharp"> try {
 Class.forName("my.package.Foo");
 // it exists on the classpath
 } catch(ClassNotFoundException e) {
 // it does not exist on the classpath
 }
</code></pre>
the static initializer block of "Foo" is kicked off. Is there a way to determine whether a class "my.package.Foo" is on the classpath without kicking off its static initializer?

I&#39;m using Mockito in some tests.

I have the following classes: 

    class BaseService {  
        public void save() {...}  
    }
     
    public Childservice extends BaseService {  
        public void save(){  
            //some code  
            super.save();
        }  
    }   

I want to mock only the second call (`super.save`) of `ChildService`. The first call must call the real method. Is there a way to do that?

Mockito How to mock only the call of a method of the superclass

I need to change the date format using Java from 


     dd/MM/yyyy  to yyyy/MM/dd



How can I change the date format in Java?

Does anyone know of a Java library that can pretty print a number in milliseconds in the same way that C# does?

E.g., 123456 ms as a long would be printed as 4d1h3m5s.

How can I &quot;pretty print&quot; a Duration in Java?

Am I missing something, or does StringBuilder lack the same &quot;replace all occurrences of a string A with string B&quot; function that the normal String class does? The StringBuilder replace function isn&#39;t quite the same. Is there any way to this more efficiently without generating multiple Strings using the normal String class?

Replace all occurrences of a String using StringBuilder?

I want to access a resource like a String or a Drawable by its name and not its int id.

Which method would I use for this?

How to get a resource id with a known resource name?

I don&#39;t really need to do this, but was just wondering, is there a way to bind a decorator to all functions within a class generically, rather than explicitly stating it for every function.

I suppose it then becomes a kind of aspect, rather than a decorator and it does feel a bit odd, but was thinking for something like timing or auth it&#39;d be pretty neat.

Attaching a decorator to all functions within a class

I am looking at the implementation of an API that I am using.

I noticed that a struct is inheriting from a class and I paused to ponder on it...  

First, I didn&#39;t see in the C++ manual I studied with that a struct could inherit from another struct:

    struct A {};
    struct B : public A {};

I guess that in such a case, struct B inherits from all the data in stuct A. Can we declare public/private members in a struct?    

But I noticed this:

     class A {};
     struct B : public A {};  

From my online C++ manual:
&lt;blockquote&gt;A class is an expanded concept of a data structure: instead of holding only data, it can hold &lt;strong&gt;both&lt;/strong&gt; data &lt;strong&gt;and functions.&lt;/strong&gt; &lt;/blockquote&gt;

Is the above inheritance valid even if class A has some member functions? What happen to the functions when a struct inherit them?  And what about the reverse: a class inheriting from a struct?  

Practically speaking, I have this:  

    struct user_messages {
      std::list&lt;std::string&gt; messages;
    };

And I used to iterate over it like this &lt;code&gt;foreach message in user_messages.messages&lt;/code&gt;. 

If I want to add member functions to my struct, can I change its declaration and &quot;promote&quot; it to a class, add functions, and still iterate over my user_messages.messages as I did before?   

Obviously, I am still a newbie and I am still unclear how structs and classes interact with each other, what&#39;s the practical difference between the two, and what the inheritance rules are...





C++: Can a struct inherit from a class?

I was wondering if someone could give me an overview of why I would use them and what advantage I would gain in the process.

When is it appropriate to use C# partial classes?

I want to be able to create a class (in Python) that once initialized with ``__init__``, does not accept new attributes, but accepts modifications of existing attributes. There&#39;s several hack-ish ways I can see to do this, for example having a ``__setattr__`` method such as

    def __setattr__(self, attribute, value):
        if not attribute in self.__dict__:
            print &quot;Cannot set %s&quot; % attribute
        else:
            self.__dict__[attribute] = value

and then editing ``__dict__`` directly inside ``__init__``, but I was wondering if there is a &#39;proper&#39; way to do this?

Prevent creating new attributes outside __init__

Is it possible to get the object name too?

    #include&lt;cstdio&gt;
    
    class one {
    public:
        int no_of_students;
        one() { no_of_students = 0; }
        void new_admission() { no_of_students++; }
    };
    
    int main() {
        one A;
        for(int i = 0; i &lt; 99; i++) {
            A.new_admission();
        }
        cout&lt;&lt;&quot;class&quot;&lt;&lt;[classname]&lt;&lt;&quot; &quot;&lt;&lt;[objectname]&lt;&lt;&quot;has &quot;
            &lt;&lt;A.no_of_students&lt;&lt;&quot; students&quot;;
    }

where I can fetch the names, something like 

    [classname] = A.classname() = one
    [objectname] = A.objectname() = A

**Does C++ provide any mechanism to achieve this?**

How can I get the class name from a C++ object?

I have created a minimal maven project with a single child module in eclipse helios.

In the src/test/resources folder I have put a single file &quot;install.xml&quot;. In the folder src/test/java I have created a single package with a single class that does:

      @Test
      public void doit() throws Exception {
        URL url = this.getClass().getClassLoader().getResource(&quot;install.xml&quot;);
        System.out.println(url.getPath());
    
      }

but when I run the code as a junit 4 unit test I just get a NullPointerException. This has worked fine a million of times before. Any ideas?

I have followed this guide:

http://www.fuyun.org/2009/11/how-to-read-input-files-in-maven-junit/

but still get the same error.

this.getClass().getClassLoader().getResource(&quot;...&quot;) and NullPointerException

How can I use `ClassLoader.getResources()` to find recursivly resources from my classpath?

E.g. 

- finding all resources in the `META-INF` &quot;directory&quot;:
  Imagine something like 

  `getClass().getClassLoader().getResources(&quot;META-INF&quot;)`

 Unfortunately, this does only retrieve an `URL` to exactly this &quot;directory&quot;.

- all resources named `bla.xml` (recursivly)

  `getClass().getClassLoader().getResources(&quot;bla.xml&quot;)`

 But this returns an empty `Enumeration`.

And as a bonus question: How does `ClassLoader.getResources()` differ from `ClassLoader.getResource()`?





How to use ClassLoader.getResources() correctly?

I know this may be a silly question for experienced coders. But I have a library (an http client) that some of the other frameworks/jars used in my project require. But all of them require different major versions like:

    httpclient-v1.jar =&gt; Required by cralwer.jar
    httpclient-v2.jar =&gt; Required by restapi.jar
    httpclient-v3.jar =&gt; required by foobar.jar

Is the classloader intelligent enough to seperate them somehow? Most likely not? How does the Classloader handle this, in case a Class is the same in all three jars. Which one is loaded and why? 

Does the Classloader only pickup exactly one jar or does it mix classes arbitrarily? So for example if a class is loaded from Version-1.jar, all other classes loaded from the same classloader will all go into the same jar? 

How do you handle this problem?

Is there some trick to somehow &quot;incorporate&quot; the jars into the &quot;required.jar&quot; so that the are seen as &quot;one unit/package&quot; by the `Classloader`, or somehow linked?


Java, Classpath, Classloading =&gt; Multiple Versions of the same jar/project

I wonder what the difference is between `Class.getResource()` and `ClassLoader.getResource()`?

*edit: I especially want to know if any caching is involved on file/directory level. As in &quot;are directory listings cached in the Class version?&quot;*

AFAIK the following should essentially do the same, but they are not:

    getClass().getResource() 
    getClass().getClassLoader().getResource()

I discovered this when fiddling with some report generation code that creates a new file in `WEB-INF/classes/` from an existing file in that directory. When using the method from Class, I could find files that were there at deployment using `getClass().getResource()`, but when trying to fetch the newly created file, I recieved a null object. Browsing the directory clearly shows that the new file is there. The filenames were prepended with a forward slash as in &quot;/myFile.txt&quot;.

The `ClassLoader` version of `getResource()` on the other hand did find the generated file. From this experience it seems that there is some kind of caching of the directory listing going on. Am I right, and if so, where is this documented?

From the [API docs][1] on `Class.getResource()`
&gt; Finds a resource
&gt; with a given name. The rules for
&gt; searching resources associated with a
&gt; given class are implemented by the
&gt; defining class loader of the class.
&gt; This method delegates to this object&#39;s
&gt; class loader. If this object was
&gt; loaded by the bootstrap class loader,
&gt; the method delegates to
&gt; ClassLoader.getSystemResource(java.lang.String).

To me, this reads &quot;Class.getResource is really calling its own classloader&#39;s getResource()&quot;. Which would be the same as doing `getClass().getClassLoader().getResource()`. But it is obviously not. Could someone please provide me with some illumination into this matter?


  [1]: http://download.oracle.com/javase/1,5.0/docs/api/java/lang/Class.html#getResource%28java.lang.String%29

What is the difference between Class.getResource() and ClassLoader.getResource()?

Is there any way to make an Android application to download and use a Java library at runtime? 

Here is an example:

Imagine that the application needs to make some calculations depending on the input values. The application asks for these input values and then checks if the required `Classe`s or `Method`s are available. 

If not, it connects to a server, downloads the needed library, and loads it at runtime to calls the required methods using reflection techniques. The implementation could change depending on various criteria such as the user who is downloading the library.

Content Type	Original Author	Original Content on Stackoverflow
Question	Epaga	View Question on Stackoverflow
Solution 1 - Java	André	View Answer on Stackoverflow

Check if class exists in Java classpath without running its static initializer?

Java Problem Overview

Java Solutions

Solution 1 - Java

How to get the values of a ConfigurationSection of type NameValueSectionHandler

"x not in" vs. "not x in"

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