[`System.InvalidOperationException`][1]

&gt; The exception that is thrown when a
&gt; method call is invalid for the
&gt; object&#39;s current state.

  [1]: http://msdn.microsoft.com/en-us/library/system.invalidoperationexception.aspx

I am using link_to img tag like following

    &lt;%= link_to image_tag(&quot;Search.png&quot;, :border=&gt;0, :class =&gt; &#39;dock-item&#39;), 
    :action =&gt; &#39;search&#39;, :controller =&gt; &#39;pages&#39;%&gt;&lt;span&gt;Search&lt;/span&gt;&lt;/a&gt;


Which results in following html

    &lt;a href=&quot;/pages/search&quot;&gt;&lt;img alt=&quot;Search&quot; border=&quot;0&quot; class=&quot;dock-item&quot; 
    src=&quot;/images/Search.png?1264132800&quot; /&gt;&lt;/a&gt;&lt;span&gt;Search&lt;/span&gt;&lt;/a&gt; 

I want the class=&quot;dock-item&quot; to go to the `&lt;a&gt;` tag instead of the img tag. 

How can i change this?

**Update:**

    &lt;%= link_to image_tag(&quot;Search.png&quot;, :border=&gt;0), :action =&gt; &#39;search&#39;, 
    :controller =&gt; &#39;pages&#39;, :class =&gt; &#39;dock-item&#39; %&gt;

results in

    &lt;a href=&quot;/pages/search?class=dock-item&quot;&gt;&lt;img alt=&quot;Search&quot; border=&quot;0&quot; 
    src=&quot;/images/Search.png?1264132800&quot; /&gt;&lt;/a&gt; 



Rails: link_to image tag. how to add class to a tag

A lot of Emacs functions automatically split the screen. However, they all do so such that the windows are one on top of the other. Is there any way to make them split such that they are side-by-side by default instead?

Setting Emacs to Split Buffers Side-by-Side

Description for [`java.lang.IllegalStateException`][1] from the Java docs:

&gt; Signals that a method has been invoked at an illegal or inappropriate time. In other words, the Java environment or Java application is not in an appropriate state for the requested operation.

Is there an equivalent for [`IllegalStateException`][1] in the .NET-Framework?


  [1]: http://java.sun.com/javase/6/docs/api/java/lang/IllegalStateException.html

java.lang.IllegalStateException in .NET?

Description for <a href="http://java.sun.com/javase/6/docs/api/java/lang/IllegalStateException.html" target="_blank" rel="noopener noreferrer"><code>java.lang.IllegalStateException</code></a> from the Java docs:
> Signals that a method has been invoked at an illegal or inappropriate time. In other words, the Java environment or Java application is not in an appropriate state for the requested operation.
Is there an equivalent for <a href="http://java.sun.com/javase/6/docs/api/java/lang/IllegalStateException.html" target="_blank" rel="noopener noreferrer"><code>IllegalStateException</code></a> in the .NET-Framework?

Which is the most efficient way to traverse a collection?

    List&lt;Integer&gt;  a = new ArrayList&lt;Integer&gt;();
    for (Integer integer : a) {
      integer.toString();
    }

or

    List&lt;Integer&gt;  a = new ArrayList&lt;Integer&gt;();
    for (Iterator iterator = a.iterator(); iterator.hasNext();) {
       Integer integer = (Integer) iterator.next();
       integer.toString();
    }

Please note, that this is not an exact duplicate of &lt;a href=&quot;https://stackoverflow.com/questions/89891/what-are-the-benefits-of-the-iterator-interface-in-java&quot;&gt;this&lt;/a&gt;, &lt;a href=&quot;https://stackoverflow.com/questions/131241/why-use-iterators-instead-of-array-indices&quot;&gt;this&lt;/a&gt;, &lt;a href=&quot;https://stackoverflow.com/questions/99164/iterate-with-for-loop-or-while-loop&quot;&gt;this&lt;/a&gt;, or &lt;a href=&quot;https://stackoverflow.com/questions/1879255/traditional-for-loop-vs-iterator-in-java&quot;&gt;this&lt;/a&gt;, although one of the answers to the last question comes close. The reason that this is not a dupe, is that most of these are comparing loops where you call `get(i)` inside the loop, rather than using the iterator.

As suggested on &lt;a href=&quot;https://meta.stackexchange.com/questions/12513/stackoverflow-should-i-answer-my-own-question-or-not&quot;&gt;Meta&lt;/a&gt; I will be posting my answer to this question.

Which is more efficient, a for-each loop, or an iterator?

Is LuaJava a must for this? Or can I embed Lua into Java without it?

How can I embed Lua in Java?

I have an array of numbers from 1 to 100 (both inclusive). The size of the array is 100. The numbers are randomly added to the array, but there is one random empty slot in the array. 
What is the quickest way to find that slot as well as the number that should be put in the slot? A Java solution is preferable.

Quickest way to find missing number in an array of numbers

I was going through [Questions every good .Net developer should be able to answer][1] and was highly impressed with the content and approach of this question, and so in the same spirit, I am asking this question for Java/Java EE Developer.


**What questions** do you think should a good **Java/Java EE programmer be able to answer?**

I am marking this question as community wiki as it is not user specific and it aims to serve programming community at large. 

Looking forward for some amazing responses. 

**EDIT**: Please answer questions too, as suggested in the comments, so that people could learn something new regarding the language, too. 


  [1]: https://stackoverflow.com/questions/365489/questions-every-good-net-developer-should-be-able-to-answer

Questions every good Java/Java EE Developer should be able to answer?

&gt; **Possible Duplicate:**  
&gt; [Java: Rationale of the Object class not being declared abstract](https://stackoverflow.com/questions/710362/java-rationale-of-the-object-class-not-being-declared-abstract)  

&lt;!-- End of automatically inserted text --&gt;

Why is the Object class, which is base class of &#39;em all in Java, not abstract?

I&#39;ve had this question for a really really long time and it is asked here purely out of curiosity, that&#39;s all. Nothing in my code or anybody&#39;s code is breaking because it is not abstract, but I was wondering why they made it concrete?

Why would anyone want an &quot;instance&quot; (and not its presence a.k.a. Reference) of this Object class? One case is a poor synchronization code which uses the instance of an Object for locking (at least I used it this way once.. my bad).

Is there any practical use of an &quot;instance&quot; of an Object class? And how does its instantiation fit in OOP? What would have happened if they had marked it abstract (of course after providing implementations to its methods)?

Why java.lang.Object is not abstract?

In the neighbour post: https://stackoverflow.com/questions/501886/wpf-mvvm-newbie-how-should-the-viewmodel-close-the-form/2100824#2100824
I&#39;ve posted my vision how to close windows with MVVM usage. And now I have a question: how to open them.

I have a main window (main view). If user clicks on the &quot;Show&quot; button then &quot;Demo&quot; window (modal dialog) should be displayed. What is a preferable way to create and open windows using MVVM pattern? I see two general approaches:

The 1st one (probably the simplest). Event handler &quot;ShowButton_Click&quot; should be implemented in the code behind of the main window in way like this:   

            private void ModifyButton_Click(object sender, RoutedEventArgs e)
            {
                ShowWindow wnd = new ShowWindow(anyKindOfData);
                bool? res = wnd.ShowDialog();
                if (res != null &amp;&amp; res.Value)
                {
                    //  ... store changes if neecssary
                }
            }

 1. If we &quot;Show&quot; button state should be changed (enabled/disabled) we will need to add logic that will manage button state;
 2. The source code is very similar to &quot;old-style&quot; WinForms and MFC sources - I not sure if this is good or bad, please advise.
 3. Something else that I&#39;ve missed?

Another approach: 

In the MainWindowViewModel we will implement &quot;ShowCommand&quot; property that will return ICommand interface of the command. Comman in turn:

 - will raise &quot;ShowDialogEvent&quot;;
 - will manage button state.

This approach will be more suitable for the MVVM but will require additional coding: ViewModel class can&#39;t &quot;show dialog&quot; so MainWindowViewModel will only raise &quot;ShowDialogEvent&quot;, the MainWindowView we will need to add event handler in its MainWindow_Loaded method, something like this:

    ((MainWindowViewModel)DataContext).ShowDialogEvent += ShowDialog;

(ShowDialog - similar to the &#39;ModifyButton_Click&#39; method.)

So my questions are:
 1. Do you see any other approach?
 2. Do you think one of the listed is good or bad? (why?)

Any other thoughts are welcome.

Thanks.

The best approach to create new window in WPF using MVVM

How can I show message boxes with a &quot;Ding!&quot; sound and a red &#39;close&#39; button in it? This is what I&#39;m talking about:

[![screenshot][1]][1]

I&#39;m trying to create some custom errors and warnings, but this:

    MessageBox.Show(&quot;asdf&quot;);

doesn&#39;t seem to give me any customization options.

  [1]: http://i.stack.imgur.com/FEweg.jpg

How to show a custom error or warning message box in .NET Winforms?

In my MSBuild script I need to pass the full directory as a parameter. How can I get it? 

Example: I am running the script from *C:\dev*, and I want a relative path, *temp*, so I am after *C:\dev\temp*.

Note: I don&#39;t know from which folder the script will be run.




How can I get the current directory in an MSBuild script?

Why do we need boxing and unboxing in C#?

I know what boxing and unboxing is, but I can&#39;t comprehend the real use of it. Why and where should I use it?

    short s = 25;

    object objshort = s;  //Boxing

    short anothershort = (short)objshort;  //Unboxing


Why do we need boxing and unboxing in C#?

What am I supposed to use when handling a value in C#, which is bigint for an SQL&amp;nbsp;Server database?


What is the equivalent of bigint in C#?

I&#39;m getting a strange error on my webserver for seemingly every file but the .aspx files.

Here is an example. Just replace &#39;/robots.txt&#39; with any .jpg name or .gif or whatever and you&#39;ll get the idea:

&gt; The controller for path &#39;/robots.txt&#39;
&gt; was not found or does not implement
&gt; IController.

I&#39;m sure it&#39;s something to do with how I&#39;ve setup routing but I&#39;m not sure what exactly I need to do about it.

Also, this is a mixed MVC and WebForms site, if that makes a difference.

I&#39;m getting a &quot;Does not implement IController&quot; error on images and robots.txt in MVC2

**Given this stack trace snippet**

&gt; Caused by: java.net.SocketException:
&gt; Software caused connection abort:
&gt; socket write error &lt;br&gt;&amp;nbsp;at
&gt; java.net.SocketOutputStream.socketWrite0(Native
&gt; Method)

**I tried to answer the following questions:**

 1. What code is throwing this exception? (JVM?/Tomcat?/My code?)
 2. What causes this exception to be thrown?

**Regarding #1:** 

Sun&#39;s JVM source doesn&#39;t contain this exact message, but I think the text *Software caused connection abort: socket write error* is from the native implementation of `SocketOutputStream`:

    private native void socketWrite0(FileDescriptor fd, byte[] b, int off,
				     int len) throws IOException;


**Regarding #2**

My guess is that it is caused when the client has terminated the connection, before getting the full response (e.g. sent a request, but before getting the full response, it got closed / terminated / offline)

**Questions:**

 1. Are the above assumptions correct (#1 and #2)?
 2. Can this be diffrentiated from the situation: &quot;could not write to the client, due to a network error on the *server* side&quot;? or would that render the same error message?
 3. And most important: **Is there an official document (e.g from Sun) stating the above?**

I need to have a proof that this stack trace is the socket client&#39;s &quot;fault&quot;, and there is nothing that the server could have done to avoid it. (except catching the exception, or using a non Sun JVM SocketOutputStream, though both don&#39;t really avoid the fact the client has terminated)


Official reasons for &quot;Software caused connection abort: socket write error&quot;

I&#39;ve read and re-read Java Concurrency in Practice, I&#39;ve read several threads here on the subject, I&#39;ve read the IBM article [Dealing with InterruptedException][1] and yet there&#39;s something I&#39;m simply not grasping which I think can be broken down into two questions:

 1. If I&#39;m never ever interrupting other threads myself, what can trigger an *InterruptedException*?

 2. If I&#39;m never ever interrupting other threads myself using *interrupt()* (say because I&#39;m using other means to cancel my working threads, like poison pills and *while (!cancelled)* style loop [as both explained in JCIP]), what does an *InterruptedException* then mean?  What am I supposed to do upon catching one?  Shutdown my app?  

  [1]: http://www.ibm.com/developerworks/java/library/j-jtp05236.html

Who is calling the Java Thread interrupt() method if I&#39;m not?

I&#39;ve heard and read many times that it is better to catch an exception as reference-to-const rather than as reference. Why is:

    try {
        // stuff
    } catch (const std::exception&amp; e) {
        // stuff
    }

better than:

    try {
        // stuff
    } catch (std::exception&amp; e) {
        // stuff
    }



Why catch an exception as reference-to-const?

I am trying to access HTTP link using `HttpURLConnection` in Android to download a file, but I am getting this warning in `LogCat`:

&gt;WARN/System.err(223): java.net.SocketException: Permission denied (maybe missing INTERNET permission) 

I have added `android.Manifest.permission` to my application but it&#39;s still giving the same exception.

Content Type	Original Author	Original Content on Stackoverflow
Question	Bob	View Question on Stackoverflow
Solution 1 - Java	Tamas Czinege	View Answer on Stackoverflow

java.lang.IllegalStateException in .NET?

Java Problem Overview

Java Solutions

Solution 1 - Java

Setting Emacs to Split Buffers Side-by-Side

Rails: link_to image tag. how to add class to a tag

Attributions