In your case, as you are trying to access it on your local machine,so it will return that value. But let one of your friend access it, and you will receive the expected result with `getRemoteAddr`  


From the javadoc:

[getRemoteAddr][1] - Returns the IP address of the client or last proxy that sent the request


[getLocalAddr][2] - Returns the IP address of the interface on which the request was received.


  [1]: http://docs.oracle.com/javaee/6/api/javax/servlet/ServletRequest.html#getRemoteAddr%28%29
  [2]: http://docs.oracle.com/javaee/6/api/javax/servlet/ServletRequest.html#getLocalAddr%28%29

As we move over to IPv6 from IPv4, they are changing the loopback address (localhost) to `0:0:0:0:0:0:0:1` from `127.0.0.1` thats why you are getting this address.

As for the functions:

 - `getRemoteAddr()` returns the clients IP
   
 - `getLocalAddr()` returns the IP of the server the application is
   running on

[**getRemoteAddr()**][1] solves your purpose but if client is behind any proxy then you will get IP address of proxy :

    

&gt; Returns the Internet Protocol (IP) address of the client or last proxy
&gt; that sent the request.



**[getLocalAddr][2]()** returns the IP of the server the application is running on. 


  [1]: http://docs.oracle.com/javaee/6/api/javax/servlet/ServletRequest.html#getRemoteAddr%28%29
  [2]: http://docs.oracle.com/javaee/6/api/javax/servlet/ServletRequest.html#getLocalAddr%28%29

I was asked to write my own implementation to remove duplicated values in an array. Here is what I have created. But after tests with 1,000,000 elements it took very long time to finish. Is there something that I can do to improve my algorithm or any bugs to remove ? 

**I need to write my own implementation - not to [use `Set`](https://stackoverflow.com/questions/10056729/java-remove-duplicates-from-an-array), `HashSet` etc. Or any other tools such as iterators. Simply an array to remove duplicates.**


    public static int[] removeDuplicates(int[] arr) {
    
        int end = arr.length;
    
        for (int i = 0; i &lt; end; i++) {
            for (int j = i + 1; j &lt; end; j++) {
                if (arr[i] == arr[j]) {                  
                    int shiftLeft = j;
                    for (int k = j+1; k &lt; end; k++, shiftLeft++) {
                        arr[shiftLeft] = arr[k];
                    }
                    end--;
                    j--;
                }
            }
        }
    
        int[] whitelist = new int[end];
        for(int i = 0; i &lt; end; i++){
            whitelist[i] = arr[i];
        }
        return whitelist;
    }

How to efficiently remove duplicates from an array without using Set

[Python requests][1] is a good module to ease my web REST API access programming, I usually do like below

&lt;!-- language: lang-py --&gt;

    import json
    url = &#39;https://api.github.com/some/endpoint&#39;
    payload = {&#39;some&#39;: &#39;data&#39;}
    headers = {&#39;Content-type&#39;: &#39;application/json&#39;, &#39;Accept&#39;: &#39;application/json&#39;}

    r = requests.post(url, data=json.dumps(payload), headers=headers)

And when there is error comes out, I want to see what happen behind it. Constructing the `curl` command to reproduce in command line is the common way, since this is the standard way which is most described in RESP API document

&lt;!-- language: lang-py --&gt;

    try:
        r = requests.post(url, data=json.dumps(payload), headers=headers)
    except Exception as ex:
        print &quot;try to use curl command below to reproduce&quot;
        print curl_request(url,&quot;POST&quot;,headers,payload)

It will be nice I can generate `curl` command sample for this request, see good example in [libcloud&#39;s debug][2], I can&#39;t find a simple way to construct, below are the method I want to create by myself.

&lt;!-- language: lang-py --&gt;

    # below code is just pseudo code, not correct 
    def curl_request(url,method,headers,payloads):
        # construct curl sample from requests&#39; structure
        # $ curl -v -H &quot;Accept: application/json&quot; -H &quot;Content-type: application/json&quot; 
        # -d &#39;{&quot;some&quot;:&quot;data&quot;}&#39; 
        # -X POST https://api.github.com/some/endpoint
        request = &quot;curl -v &quot;
        for header in headers:
            print header
            request = request + &#39;-H &quot;&#39; + header + &quot;: &quot; + headers[header] + &#39;&quot; &#39;
        for payload in payloads:
            request = request + &#39;-d {} &quot;&#39; + payload + &quot;: &quot; + payloads[payload] + &#39;&quot; &#39;         
        request = request + &quot;-X %s %s&quot; % (method,url)
        return request

It will also be nice if we have method in `requests` already

----------

Below are the final solution get the answer, works for me. Show it here for your reference

&lt;!-- language: lang-py --&gt;

    def curl_request(url,method,headers,payloads):
        # construct the curl command from request
        command = &quot;curl -v -H {headers} {data} -X {method} {uri}&quot;
        data = &quot;&quot; 
        if payloads:
            payload_list = [&#39;&quot;{0}&quot;:&quot;{1}&quot;&#39;.format(k,v) for k,v in payloads.items()]
            data = &quot; -d &#39;{&quot; + &quot;, &quot;.join(payload_list) + &quot;}&#39;&quot;
        header_list = [&#39;&quot;{0}: {1}&quot;&#39;.format(k, v) for k, v in headers.items()]
        header = &quot; -H &quot;.join(header_list)
        print command.format(method=method, headers=header, data=data, uri=url)    

  [1]: http://www.python-requests.org/
  [2]: http://libcloud.apache.org/docs/debugging.html

how to construct the curl command from python requests module?

I am trying to print the IP adress of the logged user in my webApplication. If a user connects from another PC (which is under the same network, as the web application is running in my pc) using the IP address `192.168.10.120:8080/WebApplication` the code `request.getRemoteAddr()` or `request.getLocalAddr())` returns his IP address. When I log in from my pc which run the web application, I get this IP address 0:0:0:0:0:0:0:1. &lt;Br/&gt;&lt;Br/&gt; Why is that?  And what&#39;s the difference between these commands (which should I use?).Thank you a lot!

Using request.getRemoteAddr() returns 0:0:0:0:0:0:0:1

<p>I am trying to print the IP adress of the logged user in my webApplication. If a user connects from another PC (which is under the same network, as the web application is running in my pc) using the IP address <code>192.168.10.120:8080/WebApplication</code> the code <code>request.getRemoteAddr()</code> or <code>request.getLocalAddr())</code> returns his IP address. When I log in from my pc which run the web application, I get this IP address 0:0:0:0:0:0:0:1. <br><br> Why is that?  And what's the difference between these commands (which should I use?).Thank you a lot!</p>


It is mentioned at multiple posts: improper use of `ThreadLocal` causes Memory Leak. I am struggling to understand how Memory Leak would happen using `ThreadLocal`. 


The only scenario I have figured out it as below:

&gt; A web-server maintains a pool of Threads (e.g. for servlets). Those threads can create memory leak if the variables in `ThreadLocal` are not removed because Threads do not die.

This scenario does not mention &quot;Perm Space&quot; memory leak. Is that the only (major) use case of memory leak? 

ThreadLocal &amp; Memory Leak

I am trying to understand this code block. In the first one, what is it we are looking for in the expression?

My understanding is that it is any character (0 or more times *) followed by any number between 0 and 9 (one or more times +) followed by any character (0 or more times *).

When this is executed the result is:

&lt;!-- language: lang-none --&gt;

    Found value: This order was placed for QT3000! OK?
    Found value: This order was placed for QT300
    Found value: 0

Could someone please go through this with me?

What is the advantage of using Capturing groups?


    import java.util.regex.Matcher;
    import java.util.regex.Pattern;

    public class RegexTut3 {

	    public static void main(String args[]) {
		    String line = &quot;This order was placed for QT3000! OK?&quot;; 
		    String pattern = &quot;(.*)(\\d+)(.*)&quot;;

		    // Create a Pattern object
		    Pattern r = Pattern.compile(pattern);

		    // Now create matcher object.
		    Matcher m = r.matcher(line);

		    if (m.find()) {
			    System.out.println(&quot;Found value: &quot; + m.group(0));
			    System.out.println(&quot;Found value: &quot; + m.group(1));
			    System.out.println(&quot;Found value: &quot; + m.group(2));
		    } else {
			    System.out.println(&quot;NO MATCH&quot;);
		    }
	    }

    }

Java Regex Capturing Groups

I&#39;ve tried both the examples in Oracle&#39;s [Java Tutorials][1]. They both compile fine, but at run time, both come up with this error:

```lang-none
Exception in thread &quot;main&quot; java.lang.NoClassDefFoundError: graphics/shapes/Square
    at Main.main(Main.java:7)
Caused by: java.lang.ClassNotFoundException: graphics.shapes.Square
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 1 more
```

I think I might have the `Main.java` file in the wrong folder.

Here is the directory hierarchy:

```lang-none
graphics
├ Main.java
├ shapes
|   ├ Square.java
|   ├ Triangle.java
├ linepoint
|   ├ Line.java
|   ├ Point.java
├ spaceobjects
|   ├ Cube.java
|   ├ RectPrism.java
```

And here is `Main.java`:

    import graphics.shapes.*;
    import graphics.linepoint.*
    import graphics.spaceobjects.*;

    public class Main {
        public static void main(String args[]) {
            Square s = new Square(2, 3, 15);
            Line l = new Line(1, 5, 2, 3);
            Cube c = new Cube(13, 32, 22);
        }
    }

What am I doing wrong here?

**UPDATE**

After I put put the `Main` class into the `graphics` package (I added `package graphics;` to it), set the classpath to &quot;_test&quot; (folder containing graphics), compiled it, and ran it using `java graphics.Main` (from the command line), it worked.

**Really late UPDATE #2**

I wasn&#39;t using [Eclipse][2] (just [Notepad++][3] and the JDK), and the above update solved my problem. However, it seems that many of these answers are for Eclipse and [IntelliJ IDEA][4], but they have similar concepts.

  [1]: http://docs.oracle.com/javase/tutorial
  [2]: https://en.wikipedia.org/wiki/Eclipse_%28software%29
  [3]: https://en.wikipedia.org/wiki/Notepad%2B%2B
  [4]: https://en.wikipedia.org/wiki/IntelliJ_IDEA




How can I solve &quot;java.lang.NoClassDefFoundError&quot;?

Below is a code snippet,

    int a = 1;
    char b = (char) a;
    System.out.println(b);

But what I get is empty output.

    int a = &#39;1&#39;;
    char b = (char) a;
    System.out.println(b);

I will get 1 as my output. 

Can somebody explain this? And if I want to convert an int to a char as in the first snippet, what should I do?

Convert int to char in java

I am currently implementing a small Spring MVC PoC, and I would like to use JSF as the view technology since most people in my company are used to a J2EE with Primefaces environment.

Does Spring MVC 3 support JSF, or simply JSP? I have read multiple articles mixing the two.

My need is to create an appealing UI. Is there a simple way to do this using Spring MVC with the JSP as the view technology?

Our application uses schedules/calendars in multiples pages. It&#39;s basically a time management APP



Using JSF as view technology of Spring MVC

I want to get the value of `HashMap` based on key.&lt;br&gt;

    HashMap&lt;String, ArrayList&lt;String&gt;&gt; map 
        = new HashMap&lt;String, ArrayList&lt;String&gt;&gt;();
    ArrayList&lt;String&gt; arrayList = new ArrayList&lt;String&gt;();
        
    map.put(&quot;key&quot;, arrayList);
    request.setAttribute(&quot;key&quot;, map);

What i did is&lt;br&gt;

    &lt;c:forEach var=&quot;map&quot; items=&quot;${requestScope.key}&quot;&gt;
    	&lt;c:forEach var=&quot;hash&quot; items=&quot;${map.value}&quot;&gt;
    		&lt;option&gt;&lt;c:out value=&quot;${hash}&quot;/&gt;&lt;/option&gt;
    	&lt;/c:forEach&gt;
    &lt;/c:forEach&gt;

But it seems it&#39;s printing everything, what i want to do is to get the value depends on key like: `hash.key` or something

&lt;b&gt;UPDATE:&lt;/b&gt;&lt;br&gt;
I did something like this but it still doesn&#39;t work

    &lt;c:forEach var=&quot;map&quot; items=&quot;${requestScope.key}&quot;&gt;
        &lt;c:forEach var=&quot;hash&quot; items=&quot;${map[&#39;key&#39;]}&quot;&gt;
            &lt;option&gt;&lt;c:out value=&quot;${hash}&quot;/&gt;&lt;/option&gt;
        &lt;/c:forEach&gt;
    &lt;/c:forEach&gt;

and the StackTrace: `Property &#39;External&#39; not found on type java.util.HashMap$Entry` &lt;br&gt;
I&#39;m pretty sure that there is really that kind of key.

Get value from hashmap based on key to JSTL

I have a value set in the `request` object like the following,

    String[] categoriesList=null;
    categoriesList = engine.getCategoryNamesArray();
    request.setAttribute(&quot;categoriesList&quot;, categoriesList );

and this is how I iterate in jsp page

    &lt;% if(request.getAttribute(&quot;categoriesList&quot;) != null) { %&gt;
    &lt;c:forEach var=&quot;categoryName&quot; items=&quot;${categoriesList}&quot;&gt;
       &lt;li&gt;&lt;a onclick=&quot;getCategoryIndex()&quot; href=&quot;#&quot;&gt;${categoryName}&lt;/a&gt;&lt;/li&gt;
    &lt;/c:forEach&gt;
    &lt;% }%&gt;

How do I get index of each element and pass it to JavaScript function `onclick=&quot;getCategoryIndex()&quot;`.


How to get a index value from foreach loop in jstl

I have a JSP file and in that file I am including another JSP file:

    &lt;c:forEach var=&quot;instanceVar&quot; items=&quot;${instanceList}&quot;&gt;
        &lt;c:set var=&quot;instance&quot;&gt;&lt;jsp:include page=&quot;instance.jsp&quot;/&gt;&lt;/c:set&gt;
        ...
    &lt;/c:forEach

&lt;br&gt;
In the file _instance.jsp_ I want to use a variable `instanceVar`. I want to do it using JSTL. Is there any way to do this?



Passing parameters to another JSP file using &lt;jsp:include&gt; tag

I can&#39;t get tomcat7 to compile jsps. It till run the example servlets just fine and the service is up and running. I am running oracle java 8.

Can anyone point me in the right direction?

Here is the stacktrace:

    type Exception report
    
    message Unable to compile class for JSP:
    
    description The server encountered an internal error that prevented it from fulfilling this request.
    
    exception
    
    org.apache.jasper.JasperException: Unable to compile class for JSP: 
    
    An error occurred at line: 1 in the generated java file
    The type java.util.Map$Entry cannot be resolved. It is indirectly referenced from required .class files
    
    Stacktrace:
    	org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:102)
    	org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:331)
    	org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:468)
    	org.apache.jasper.compiler.Compiler.compile(Compiler.java:378)
    	org.apache.jasper.compiler.Compiler.compile(Compiler.java:353)
    	org.apache.jasper.compiler.Compiler.compile(Compiler.java:340)
    	org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:646)
    	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:357)
    	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    	javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    note The full stack trace of the root cause is available in the Apache Tomcat/7.0.35 logs.

---

The code looks like this and it&#39;s the sample code from tomcat7 so my guess is that it&#39;s correct. 

    &lt;%@ taglib prefix=&quot;mytag&quot; uri=&quot;/WEB-INF/jsp2/jsp2-example-taglib.tld&quot; %&gt;
    &lt;html&gt;
    &lt;head&gt;
      &lt;title&gt;JSP 2.0 Examples - Hello World SimpleTag Handler&lt;/title&gt;
    &lt;/head&gt;
    &lt;body&gt;
    &lt;h1&gt;JSP 2.0 Examples - Hello World SimpleTag Handler&lt;/h1&gt;
    &lt;hr&gt;
    &lt;p&gt;This tag handler simply echos &quot;Hello, World!&quot;  It&#39;s an example of
    a very basic SimpleTag handler with no body.&lt;/p&gt;
    &lt;br&gt;
    &lt;b&gt;&lt;u&gt;Result:&lt;/u&gt;&lt;/b&gt;
    &lt;mytag:helloWorld/&gt;
    &lt;/body&gt;
    &lt;/html&gt;


Unable to compile class for JSP: The type java.util.Map$Entry cannot be resolved. It is indirectly referenced from required .class files

I am developing one app, and what I think I wanna do is receive data from server database in android. So I started to run some tutorials. I found one that is doing pretty much what I want. 
But I am getting: 

    detailMessage	&quot;failed to connect to localhost/127.0.0.1 (port 8080): connect failed: ECONNREFUSED (Connection refused)&quot; (id=830021648792)	

Whole code of this tutorial is here [link][1]

Error occurs on : 

`OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream());`


  [1]: http://veereshr.com/Android/AndroidToServlet

I checked that:

 - firewall is disabled
 - ping is working
 - connection string is exactly the same as when I run the servlet from server admin interface - `http://localhost:8080/Requestor/RQSRV`
-the servlet is running 

My configuration :


 - Server : Glass Fish 4.0
 - Android App - Developed in Eclipse
 - Servlet - Developed in NetBeans



connect failed: ECONNREFUSED

I have this piece of code:

    resp.addHeader(&quot;Content-Disposition&quot;, &quot;inline; filename=&quot; + fileName);

When the file name is &quot;a_b_c.doc&quot; or &quot;abc.doc&quot; the name of the downloaded file is displayed correctly. However, when the file name is &quot;a b c .doc&quot; the name of the downloaded file is only &quot;a&quot;.

How can we solve this? 

How to set filename containing spaces in Content-Disposition header

I read [here][1] that one should not save the file in the server anyway as it is not portable, transactional and requires external parameters. However, given that I need a tmp solution for tomcat (7) and that I have (relative) control over the server machine I want to know :

 - What is the best place to save the file ? Should I save it in `/WEB-INF/uploads` (advised against [here][2]) or someplace under `$CATALINA_BASE` (see [here][3]) or ... ? The JavaEE 6 tutorial [gets the path from the user][4] (:wtf:). NB : The file should not be downloadable by any means.
   
 - Should I set up a config parameter as detailed [here][5] ? I&#39;d appreciate some code (I&#39;d rather give it a relative path - so it is at least Tomcat portable) - [`Part.write()`][6] looks promising - but apparently needs a absolute path

 - I&#39;d be interested in an exposition of the disadvantages of this approach vs a database/JCR repository one

Unfortunately the [FileServlet][7]  by @BalusC concentrates on downloading files, while his [answer][8] on uploading files skips the part on where to save the file.

A solution easily convertible to use a DB or a JCR implementation (like [jackrabbit][9]) would be preferable.


  [1]: https://stackoverflow.com/a/2663855/281545
  [2]: https://stackoverflow.com/a/13617442/281545
  [3]: https://stackoverflow.com/a/1047581/281545
  [4]: http://docs.oracle.com/javaee/6/tutorial/doc/glraq.html#gmhbq
  [5]: https://stackoverflow.com/a/2663250/281545
  [6]: http://docs.oracle.com/javaee/6/api/javax/servlet/http/Part.html#write%28java.lang.String%29
  [7]: http://balusc.blogspot.gr/2009/02/fileservlet-supporting-resume-and.html
  [8]: https://stackoverflow.com/a/2424824/281545
  [9]: http://jackrabbit.apache.org/frequently-asked-questions.html

Recommended way to save uploaded files in a servlet application

Could you help me write spring mvc style analog of this code?
   

     session.setAttribute(&quot;name&quot;,&quot;value&quot;);

And how to add an element that is annotated by `@ModelAttribute` annotation to session and then get access to it?


Content Type	Original Author	Original Content on Stackoverflow
Question	yaylitzis	View Question on Stackoverflow
Solution 1 - Java	Abubakkar	View Answer on Stackoverflow
Solution 2 - Java	Robert Pounder	View Answer on Stackoverflow
Solution 3 - Java	Ankur Lathi	View Answer on Stackoverflow

Using request.getRemoteAddr() returns 0:0:0:0:0:0:0:1

Java Problem Overview

Java Solutions

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Solution 2 - Java

Solution 3 - Java

how to construct the curl command from python requests module?

How to efficiently remove duplicates from an array without using Set

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