I am using slf4j for logging in my application.
I get the purpose of slf4j. I would like to know how to find out which logging-library slf4j is currently binding to. I have log4j in my referenced libraries. I am assuming that slf4j has bound itself to log4j.

What I would like to know is, is there any way to explicitly confirm this binding?

How to find which library slf4j has bound itself to?

My question seems to be easily answerable, but there are several good solutions.
I like to choose the &#39;best&#39; one.

Available frameworks (feel free to suggest more):
=================================================

 - [Androlog][1]
 - [SLF4J Android][2]
 - [Log4J - Android][3]

Pros/Cons:
==========

Androlog:
---------

 - Pro: Similar to Android logging framework, so there are only small changes in the existing code; Able to send crash reports with more detail in the error report (the logs around the exception); Nice logs
 - Con: No standard java &quot;getLogger&quot; approach; Production configuration achievable by uploading property file to sdcard; I need to call init logging manually; Need to create LOG_TAG like constants, or hack it to create log tag constants by Aspect to achieve the standard behavior: tags are the class names; When logging is a business requirement, we need to test it. Testing static calls on Android nearly impossible; Logger can not be injected by framework

Log4J-Android:
--------------
 - Pro: Standard way to log in Java; Compatible with SLF4J; Able to parse property files; 
 - Con: No built-in crash report system; Seems to me: its not commonly used, so it might me dangerous to use it;

SLF4J-Android:
--------------
 - Pro: Seems to be developed by more people like Log4J-Android; The `logger.debug(&quot;Some log message. Details: {}&quot;, someObject.toString());` is a good, and effective way to skip string concatenations if the logger is turned off; lightweight logger binding that delegates to `android.util.Log`.
 - Con: Auto generated log tags that are &lt;= 23 characters long due to a length restriction of log tags on the Android platform (e.g., `com.example.myapp.MyClass` tag translated to `c*.e*.m*.MyClass`), which can result in the same log tag for different classes (e.g., `com.example.app.MyClass` and `com.example.anotherapp.MyClass` both translate to `c*.e*.a*.MyClass`); No built in crash reporting system.

Besides of these, I like Androlog behavior, but I&#39;m a Java dev, familiar with log4j/slf4j.
We will definitely need crash report system, but there are several frameworks for crash reporting (beside of android default crash report).

I can combine some of them, for example use Log4J android, but create an appender to use the androlog framework, but sooner or later it will be a mess, which should be avoided.

Thanks for your suggestions, I hope the results will help decide others in the future.

Edit: As mentioned below, I can combine for ex: log4j-android with slf4j (whitch I prefer to do if I&#39;ll use log4j, because the log formatting support (&quot;{}&quot;,...) ), but it does not answers the question. I have to choose a framework, then I can decorate it with the SLF4J facade.

  [1]: http://akquinet.github.com/androlog/
  [2]: http://www.slf4j.org/android/
  [3]: http://code.google.com/p/android-logging-log4j/

Which Android logging framework to use?

What is the correct approach to log both a populated message and a stack trace of the exception?

    logger.error(
        &quot;\ncontext info one two three: {} {} {}\n&quot;,
        new Object[] {&quot;1&quot;, &quot;2&quot;, &quot;3&quot;},
        new Exception(&quot;something went wrong&quot;));

I&#39;d like to produce an output similar to this:

&lt;!-- language: none --&gt;

    context info one two three: 1 2 3
    java.lang.Exception: something went wrong
    stacktrace 0
    stacktrace 1
    stacktrace ...

My SLF4J version is 1.6.1.

How to log formatted message, object array, exception?

The &quot;Hello World&quot; example from [SLF4J][1] is not working for me. I guess this is because I added slf4j-log4 to my classpath. Should I configure log4j directly for the hello world to work?

    log4j:WARN No appenders could be found for logger (HelloWorld).
    log4j:WARN Please initialize the log4j system properly.
    log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

**Update**: I added log4j initialization, and it still doesn&#39;t work:

    public static void main(String[] params) {
            org.apache.log4j.Logger.getRootLogger().addAppender(new ConsoleAppender());
            Logger logger = org.slf4j.LoggerFactory.getLogger(TestBase.class);
            logger.info(&quot;Hello World&quot;);
        }

And I&#39;m getting:

    log4j:ERROR No output stream or file set for the appender named [null].

  [1]: http://www.slf4j.org/manual.html


How to get SLF4J &quot;Hello World&quot; working with log4j?

I am trying to run GWT RequestFactory and facing this error:

    ClassNotFoundException: org.slf4j.LoggerFactory

I have tried to download *slf4j-api-1.3.1.jar* but it didnt resolve the issue 

Any idea exactly which jar I need to download ?

ClassNotFoundException: org.slf4j.LoggerFactory

My scala/sbt project uses grizzled-slf4j and logback. A third-party dependency uses Apache Commons Logging.

With Java/Maven, I would use jcl-over-slf4j and logback-classic so that I can use logback as the unified logging backend.

I would also eliminate the commons-logging dependency that the third-party lib would let sbt pull in. I do the following in Maven (which is recommended by http://www.slf4j.org/faq.html#excludingJCL):

    &lt;dependency&gt;
        &lt;groupId&gt;commons-logging&lt;/groupId&gt;
        &lt;artifactId&gt;commons-logging&lt;/artifactId&gt;
        &lt;version&gt;1.1.1&lt;/version&gt;
        &lt;scope&gt;provided&lt;/scope&gt;
    &lt;/dependency&gt;

And the question is, how to do the same with sbt?

How to exclude commons-logging from a scala/sbt/slf4j project?

I&#39;m happily using SLF4J with logback and use **2 appenders** for the **ROOT** logger.

    &lt;root level=&quot;DEBUG&quot;&gt;
    	&lt;appender-ref ref=&quot;STDOUT&quot; /&gt;
    	&lt;appender-ref ref=&quot;FILE&quot; /&gt;
    &lt;/root&gt;

**How could we have different log-levels for both appenders? I still need all ROOT-logger messages.**

 - *DEBUG*-level for STDOUT
 - *INFO*-level for FILE

All log&#39;s need to be part of the output (so the ROOT logger is needed).

How to create 2 different ROOT loggers with logback?

I&#39;m trying to run the sample tiles example given [here][1].


  [1]: http://richardbarabe.wordpress.com/2009/02/17/apache-tiles-2-a-brief-example/

Below is my POM.xml:

    &lt;dependencies&gt;
    		&lt;dependency&gt;
    			&lt;groupId&gt;junit&lt;/groupId&gt;
    			&lt;artifactId&gt;junit&lt;/artifactId&gt;
    			&lt;version&gt;3.8.1&lt;/version&gt;
    			&lt;scope&gt;test&lt;/scope&gt;
    		&lt;/dependency&gt;
    		&lt;dependency&gt;
    			&lt;groupId&gt;org.apache.tiles&lt;/groupId&gt;
    			&lt;artifactId&gt;tiles-api&lt;/artifactId&gt;
    			&lt;version&gt;2.1.2&lt;/version&gt;
    		&lt;/dependency&gt;
    		&lt;dependency&gt;
    			&lt;groupId&gt;org.apache.tiles&lt;/groupId&gt;
    			&lt;artifactId&gt;tiles-core&lt;/artifactId&gt;
    			&lt;version&gt;2.1.2&lt;/version&gt;
    		&lt;/dependency&gt;
    		&lt;dependency&gt;
    			&lt;groupId&gt;org.apache.tiles&lt;/groupId&gt;
    			&lt;artifactId&gt;tiles-jsp&lt;/artifactId&gt;
    			&lt;version&gt;2.1.2&lt;/version&gt;
    		&lt;/dependency&gt;
    		&lt;dependency&gt;
    			&lt;groupId&gt;org.slf4j&lt;/groupId&gt;
    			&lt;artifactId&gt;slf4j-api&lt;/artifactId&gt;
    			&lt;version&gt;1.5.2&lt;/version&gt;
    		&lt;/dependency&gt;


When I&#39;m trying to run the example the below error is thrown:

    Sep 17, 2010 11:59:43 PM org.apache.catalina.core.StandardContext listenerStart
    SEVERE: Error configuring application listener of class      org.apache.tiles.web.startup.TilesListener
    java.lang.NoClassDefFoundError: org/slf4j/impl/StaticLoggerBinder
	at org.slf4j.LoggerFactory.&lt;clinit&gt;(LoggerFactory.java:60)
	at org.apache.commons.logging.impl.SLF4JLogFactory.getInstance(SLF4JLogFactory.java:155)
	at org.apache.commons.logging.impl.SLF4JLogFactory.getInstance(SLF4JLogFactory.java:131)
	at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:685)
	at org.apache.tiles.web.startup.TilesListener.&lt;init&gt;(TilesListener.java:49)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
	at java.lang.reflect.Constructor.newInstance(Unknown Source)
	at java.lang.Class.newInstance0(Unknown Source)
	at java.lang.Class.newInstance(Unknown Source)


Any idea?

I spent 30 minutes googling for this but could not find a possible sollution.


Please help me...

NoClassDefFoundError: org/slf4j/impl/StaticLoggerBinder

I&#39;m getting the following error. It seems there are multiple logging frameworks bound to slf4j. Not sure how to resolve this. Any help is greatly appreciated.

    SLF4J: Class path contains multiple SLF4J bindings.
    SLF4J: Found binding in [jar:file:/C:/Users/admin/.m2/repository/org/slf4j/slf4j-log4j12/1.6.4/slf4j-log4j12-1.6.4.jar!/org/slf4j/impl/StaticLoggerBinder.class]
    SLF4J: Found binding in [jar:file:/C:/Users/admin/.m2/repository/org/slf4j/slf4j-log4j12/1.6.1/slf4j-log4j12-1.6.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]
    SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.



SLF4J: Class path contains multiple SLF4J bindings

I am trying to use SLF4J (with `log4j` binding) for the first time.

I would like to configure 3 different named Loggers that can be returned by a LoggerFactory which will log different levels and push the messages to different appenders:

* Logger 1 &quot;FileLogger&quot; logs DEBUG and appends to `DailyRollingFileAppender`
* Logger 2 &quot;TracingLogger&quot; logs TRACE+ and appends to a `JmsAppender`
* Logger 3 &quot;ErrorLogger&quot; logs ERROR+ and appends to a different `JmsAppender`

Furthermore I want them configured programmatically (in Java, as opposed to XML or a `log4j.properties` file).

I imagine that, normally, I would define these `Logger`s somewhere in some bootstrapping code, like an `init()` method. However, because I want to use `slf4j-log4j`, I&#39;m confused about where I could define loggers and make them available to the classpath.

I don&#39;t *believe* this is a violation of SLF4J&#39;s underlying purpose (as a facade), because my code using the SLF4J API won&#39;t ever know that these loggers exist. My code just makes normal calls to the SLF4J API, which then forwards them on to the log4j Loggers it finds on the classpath.

**But how do I configure those log4j Loggers on the classpath...in Java?!**


Configuring Log4j Loggers Programmatically

api 1.7 and slf4j-simple as implementation. I just can&#39;t find how to configure the logging level with this combination. 

Can anyone help out?

How to configure slf4j-simple

My application is to be deployed on both tcServer and WebSphere 6.1. This application uses ehCache and so requires slf4j as a dependency.
As a result I&#39;ve added the slf4j-api.jar (1.6) jar to my war file bundle.

The application works fine in tcServer except for the following error:

    SLF4J: Failed to load class &quot;org.slf4j.impl.StaticLoggerBinder&quot;.
    SLF4J: Defaulting to no-operation (NOP) logger implementation
    SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

However, when I deploy in WebSphere I get a `java.lang.NoClassDefFoundError: org.slf4j.impl.StaticLoggerBinder`.

Also accompanied by `Failed to load class &quot;org.slf4j.impl.StaticMDCBinder&quot;`

I&#39;ve checked the classpaths of both application servers and there is no other slf4j jar.

Does anyone have any ideas what may be happening here?

SLF4J: Failed to load class &quot;org.slf4j.impl.StaticLoggerBinder&quot;

In our software we extensively use [**MDC**][1] to track things like session IDs and user names for web requests. This works fine while running in the original thread.

However, there&#39;s a lot of things that need to be processed in the background. For that we use the `java.concurrent.ThreadPoolExecutor` and `java.util.Timer` classes along with some self-rolled *async* execution services. All these services manage their own thread pool.

This is what [Logback&#39;s manual](http://logback.qos.ch/manual/mdc.html#managedThreads) has to say about using MDC in such an environment:

&gt; A copy of the mapped diagnostic context can not always be inherited by worker threads from the initiating thread. This is the case when java.util.concurrent.Executors is used for thread management. For instance, newCachedThreadPool method creates a ThreadPoolExecutor and like other thread pooling code, it has intricate thread creation logic.
&gt; 
&gt; In such cases, it is recommended that MDC.getCopyOfContextMap() is invoked on the original (master) thread before submitting a task to the executor. When the task runs, as its first action, it should invoke MDC.setContextMapValues() to associate the stored copy of the original MDC values with the new Executor managed thread.

This would be fine, but it is a very easy to forget adding those calls, and there is no easy way to recognize the problem until it is too late. The only sign with Log4j is that you get missing MDC info in the logs, and with Logback you get stale MDC info (since the thread in the tread pool inherits its MDC from the first task that was ran on it). Both are serious problems in a production system.

I don&#39;t see our situation special in any way, yet I could not find much about this problem on the web. Apparently, this is not something that many people bump up against, so there must be a way to avoid it. What are we doing wrong here?


  [1]: http://logback.qos.ch/manual/mdc.html

How to use MDC with thread pools?

I am using logback/slf4j to do my logging. I want to parse my log file to analyze some data, so instead of parsing a great big file (mostly consisting of debug statements) I want to have two logger instances which each log to a separate file; one for analytics and one for all purpose logging. Does anyone know if this is possible with Logback, or any other logger for that matter?

Logback to log different messages to two files

I am not able to decide whether to use slf4j or not with log4j2. Based on online posts, does not look like it will have any performance hit but is it really required. 

Also these points rule in favor of log4j2:

- SLF4J forces your application to log Strings. The Log4j 2 API supports logging any CharSequence if you want to log text, but also supports logging any Object as is.
- The Log4j 2 API offers support for logging Message objects, Java 8 lambda expressions and garbage-free logging (it avoids creating vararg arrays and avoids creating Strings when logging CharSequence objects).

Is it worth to use slf4j with log4j2

I have a maven project that builds with no problems from the command line. However, when I build it with IntelliJ, I get the error:

	java: FileName.java:89: cannot find symbol
	symbol  : variable log

There is no log defined or imported in the java file, but there is a

    @Slf4j
    final public class FileName {

statement before the class body which should define the log class.

In the project structure window, classes for:

    Maven: org.slf4j:jcl-over-slf4j:1.6.1
    Maven: org.slf4j:slf4j-api:1.6.6
    Maven: org.slf4j:slf4j-log4j12:1.6.6
    Maven: org.slf4j:slf4j-simple:1.6.6

are listed under libraries and are indicated as having been downloaded and available.

Any idea why this would build with maven through the command line, but not through IntelliJ and how to resolve the issue?

Building with Lombok&#39;s @Slf4j and Intellij: Cannot find symbol log

We are using SLF4J+Logback combination at our project for a while now and are quite happy with it, but our logging strategy is fairly simple, using straightforward class based loggers and no fancy stuff like MDC or Markers.

What I want to know is if anybody in the community actually uses these features and how they are used to improve logging/filtering.

I am specially interested in where, why and how would one use&lt;sup&gt;[1]&lt;/sup&gt; Markers for logging. They strike me as a pretty neat feature for adding semantic context into the logging - e.g. while a class may be handling multiple concerns, one may use task/concern specific markers to discriminate log statements.

What may be the best practices, conventions or strategies for creating and using markers in logging.

**Update:** I guess, what I am really after is not so much _why_ to use markers, but rather the _how_ part &amp;mdash; is there some good practices of naming markers (e.g. using plain text with spaces or dash/underscore/punctuation delimited keyword style names), should there be some sort of pool of &quot;standard names&quot;, naming stuff based on the business functions. The questions I can probably figure out for myself, but if I want to use these features systematically and introduce them to a team of developers, it makes sense to have some formalizeable set of guidelines around...

---

&lt;sup&gt;[1]&lt;/sup&gt; - By asking how to _use_ markers I am not really asking how to use API (it is really quite straight forward) - I am rather referring to the more general level of how would one set up logging around using markers consistently

Best practices for using Markers in SLF4J/Logback

The first time I heard about markers was while reading:

  http://slf4j.org/faq.html

I checked available methods for the **Logger** object:

 * http://www.slf4j.org/api/org/slf4j/Logger.html
 * http://logging.apache.org/log4j/2.x/log4j-api/apidocs/org/apache/logging/log4j/Logger.html

and found interfaces:

 * http://www.slf4j.org/api/org/slf4j/Marker.html
 * http://logging.apache.org/log4j/2.x/log4j-api/apidocs/org/apache/logging/log4j/Marker.html

The more in-depth info I got from:

 * http://logback.qos.ch/manual/filters.html

but I am still confused... Note that I asked *why*, not *how* to use them, so this is not a duplicate of:

 * https://stackoverflow.com/questions/4165558/best-practices-for-using-markers-in-slf4j-logback

**UPDATE** Seems that when you use markers you are also required to write custom Java code instead doing configuration in *XML* or *.property* files...

**UPDATE 2** From http://logback.qos.ch/manual/appenders.html#OnMarkerEvaluator

    Marker notifyAdmin = MarkerFactory.getMarker(&quot;NOTIFY_ADMIN&quot;);
    logger.error(notifyAdmin,
      &quot;This is a serious an error requiring the admin&#39;s attention&quot;,
       new Exception(&quot;Just testing&quot;));

What are markers in Java Logging frameworks and what is a reason to use them?

Is there any advantage of using `{}` instead of string concatenation?

An example from slf4j


    logger.debug(&quot;Temperature set to {}. Old temperature was {}.&quot;, t, oldT);


instead of

    logger.debug(&quot;Temperature set to&quot;+ t + &quot;. Old temperature was &quot; + oldT);

I think it&#39;s about speed optimization because parameters evaluation (and string concatenation) could be avoided in runtime depending on a config file. But only two parameters are possible, then sometimes there is no other choice than string concatenation. Needing views on this issue.

Logger slf4j advantages of formatting with {} instead of string concatenation

 - Regarding *Eclipse IDE* (**Indigo**, **Juno** and **Kepler** (32 and 64 bit versions))
 - *Platforms*: **Windows**, **Ubuntu**, **Mac**
 - *m2e version*: **1.1.0.20120530-0009**, **1.2.0.20120903-1050**, **1.3.0.20130129-0926**,                
**1.4.0.20130601-0317**	

----------

**General info**
------------------------------

The above error came after updating the m2e to version 1.1. ***By removing m2e 1.1 and rolling back to m2e 1.0 everything worked fine.*** I tried to repeat the problem in Windows and Ubuntu and it gave me the exact same error. Numerous configurations of the slf4j-api and logback were tested but none seem to work. 

The error appears in any maven project **even without declaring slf4j dependency**. 

 - New Maven Project--&gt; maven-archetype-quickstart 

       **and** 

 - New Maven Project--&gt; Simple project without archetype selection 

   result to

   &lt;!-- language: java --&gt;

    SLF4J: Failed to load class &quot;org.slf4j.impl.StaticLoggerBinder&quot;.

----------

**Testing enviroments and configurations**
------------------------------
Tested with Eclipse Indigo and Eclipse Juno (32 and 64 bit both) on Mac, 32 bit on Ubuntu and 64 and 32 bit on Windows. Tested fresh installs of **Juno Classic**, **Juno Modelling tools**, **Kepler Standard**, **Kepler Modelling Tools** and produced the same error. 

The error appears with **clean**, **install**, **test**, **deploy**, **generate-sources**, **validate** , **compile** , **package**, **integration-test**, **verify** and combinations of the goal clean with the rest goals. It appears also with parameters **-e** and **-X**. There was an attempt to delete the m2e repository and download it from scratch but again without success. It should me mentioned that it was tested in 3 different machines and virtual box all the above systems but it produced the same error. 

Tried all different **logback** configurations (from 1.0.4 to 1.0.13) that resolve the **slf4j-api** and **logback-core** dependencies, but all produce the same error:

&lt;!-- language: xml --&gt;

    &lt;dependency&gt;
       &lt;groupId&gt;ch.qos.logback&lt;/groupId&gt;
       &lt;artifactId&gt;logback-classic&lt;/artifactId&gt;
       &lt;version&gt;&lt;/version&gt;
    &lt;/dependency&gt;

Tried all different (from 1.6.1 to 1.7.5 ) **slf4j-simple** configurations.

&lt;!-- language: xml --&gt;

    &lt;dependency&gt;
       &lt;groupId&gt;org.slf4j&lt;/groupId&gt;
       &lt;artifactId&gt;slf4j-simple&lt;/artifactId&gt;
       &lt;version&gt;&lt;/version&gt;
       &lt;scope&gt;compile&lt;/scope&gt;
    &lt;/dependency&gt;

Tried all different (from 1.6.1 to 1.7.5 ) **log4j-over-slf4j** configurations.

&lt;!-- language: xml --&gt;

    &lt;dependency&gt;
       &lt;groupId&gt;org.slf4j&lt;/groupId&gt;
       &lt;artifactId&gt;log4j-over-slf4j&lt;/artifactId&gt;
       &lt;version&gt;&lt;/version&gt;
       &lt;scope&gt;compile&lt;/scope&gt;
    &lt;/dependency&gt;

Tried all different (from 1.6.1 to 1.7.5 ) **slf4j-jdk14** configurations.

&lt;!-- language: xml --&gt;

    &lt;dependency&gt;
       &lt;groupId&gt;org.slf4j&lt;/groupId&gt;
       &lt;artifactId&gt;slf4j-jdk14&lt;/artifactId&gt;
       &lt;version&gt;&lt;/version&gt;
       &lt;scope&gt;compile&lt;/scope&gt;
    &lt;/dependency&gt;

Tried all different (from 1.6.1 to 1.7.5 ) **slf4j-log4j12** configurations.


&lt;!-- language: xml --&gt;

    &lt;dependency&gt;
         &lt;groupId&gt;org.slf4j&lt;/groupId&gt;
         &lt;artifactId&gt;slf4j-log4j12&lt;/artifactId&gt;
         &lt;version&gt;&lt;/version&gt;
         &lt;scope&gt;compile&lt;/scope&gt;
    &lt;/dependency&gt;


Tried **slf4j-nop 1.7.5** configuration.


&lt;!-- language: xml --&gt;

    &lt;dependency&gt;
      &lt;groupId&gt;org.slf4j&lt;/groupId&gt;
      &lt;artifactId&gt;slf4j-nop&lt;/artifactId&gt;
      &lt;version&gt;1.7.5&lt;/version&gt;
      &lt;scope&gt;compile&lt;/scope&gt;
    &lt;/dependency&gt;


***Last but not least the logs are saved and printed despite the error.***


----------


**Ways to reproduce the error**
------------------------------

 - Download Eclipse Juno, Indigo or Kepler 32 or 64 bit (All installations will
   cause the same error). 
     - Install m2e - Maven Integration for Eclipse
         - Juno - http://download.eclipse.org/releases/juno
         - Kepler - http://download.eclipse.org/releases/kepler
         - Indigo - http://download.eclipse.org/technology/m2e/releases/ (***currently unavailable***)

        **OR**
 
     - Update your m2e version to **1.1.0.20120530-0009**, or **1.2.0.20120903-1050**, or **1.3.0.20130129-0926**, or **1.4.0.20130601-0317** )
&lt;hr&gt;
     - Select File-&gt;New-&gt;Other-&gt;Maven Project-&gt;Click Next-&gt;Select      
   maven-archetype-quickstart from the catalog-&gt;Finish
     
        **OR**

     - Select File-&gt;New-&gt;Other-&gt;Maven Project-&gt;Click Next-&gt;Select Create a simple project (skip archetype selection)-&gt; Complete Artifact info-&gt; Finish
 - Right Click on the project-&gt;Runs As-&gt;clean install (or any other goal mentioned above)

The first line on the console will be 

&lt;!-- language: java --&gt;

    SLF4J: Failed to load class &quot;org.slf4j.impl.StaticLoggerBinder&quot;.
    SLF4J: Defaulting to no-operation (NOP) logger implementation
    SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.



***P.S. Existing projects will produce the same error after updating the m2e version to 1.1.0.20120530-0009***, **1.2.0.20120903-1050**, **1.3.0.20130129-0926**, **1.4.0.20130601-0317**

&lt;hr&gt;
**Updates**
------------------------------

**EDIT**

**m2e support site:** 

 - The above question was posted as a bug in m2e support site and the answer from Igor Fedorenko was that


       &gt; There are no immediate plans to suppress this message.

       For viewing the above bug please refer to [m2e official support site][1]

&lt;hr&gt;
**EDIT 2**

 - The above error indication is **present** also to **m2e** version ***1.2.0.20120903-1050***

&lt;hr&gt;
**EDIT 3**

 - The above error indication is **present** also to **m2e** version ***1.3.0.20130129-0926***


&lt;hr&gt;
**EDIT 4**

 - The above error indication is **present** also to **m2e** version ***1.4.0.20130601-0317***

&lt;hr&gt;
**EDIT 5**

             
                                  ***Reported FIXED***



 - The above error is reported as fixed for **m2e** version ***1.5.0/Luna M3***(*Target Milestone*). The version is not yet available for download. 
 - ***Luna M3*** is [scheduled for Nov. 15th][2]. 
 - Latest dev build are available [here][3]    
 - More information about the m2e milestones you can find at the [m2e main repository][4]. 


  [1]: https://bugs.eclipse.org/bugs/show_bug.cgi?id=387064
  [2]: http://wiki.eclipse.org/Luna/Simultaneous_Release_Plan#Schedule
  [3]: http://nexus.tesla.io:8081/nexus/content/sites/m2e.extras/m2e/1.5.0/N/LATEST/
  [4]: http://git.eclipse.org/c/m2e/m2e-core.git/

SLF4J: Failed to load class &quot;org.slf4j.impl.StaticLoggerBinder&quot;. error

When using log4j, the `Logger.log(Priority p, Object message)` method is available and can be used to log a message at a log level determined at runtime. We&#39;re using this fact and [this tip][1] to redirect stderr to a logger at a specific log level.

slf4j doesn&#39;t have a generic `log()` method that I can find. Does that mean there&#39;s no way to implement the above?


  [1]: http://www.mail-archive.com/log4j-user@logging.apache.org/msg05005.html

Setting log level of message at runtime in slf4j

Hibernate 3.x used [tag:slf4j] for logging. Hibernate 4.x uses [tag:jboss-logging]. I am writing a standalone application which uses Hibernate 4, and SLF4J for logging.

How can i configure Hibernate to log to SLF4J?

If that&#39;s not possible, how can i configure Hibernate&#39;s logging at all?

The Hibernate 4.1 manual [section on logging][1] starts with the warning that it is ...

&gt;  Completely out of date. Hibernate uses JBoss Logging starting in 4.0. This will get documented as we migrate this content to the Developer Guide.

... goes on to talk about SLF4J, and so is useless. Neither the [getting started guide][2] nor the [developer guide][3] talk about logging at all. Nor does the [migration guide][4].

I have looked for documentation on jboss-logging itself, but i haven&#39;t been able to find any at all. The [GitHub page is silent][5], and JBoss&#39;s [community projects page][6] doesn&#39;t even list jboss-logging. I wondered if th project&#39;s [bug tracker][7] might have any issues relating to providing documentation, but it doesn&#39;t.

The good news is that when using Hibernate 4 inside an application server, such as JBoss AS7, logging is largely taken care of for you. But how can i configure it in a standalone application?


  [1]: http://docs.jboss.org/hibernate/orm/4.1/manual/en-US/html/ch03.html#configuration-logging
  [2]: http://docs.jboss.org/hibernate/orm/4.1/quickstart/en-US/html/
  [3]: http://docs.jboss.org/hibernate/orm/4.1/devguide/en-US/html/
  [4]: https://community.jboss.org/wiki/HibernateCoreMigrationGuide40
  [5]: https://github.com/jboss-logging/jboss-logging
  [6]: http://www.jboss.org/projects
  [7]: https://issues.jboss.org/secure/IssueNavigator.jspa?reset=true&amp;jqlQuery=project%20=%20JBLOGGING%20AND%20resolution%20=%20Unresolved%20AND%20component%20is%20EMPTY%20ORDER%20BY%20priority%20DESC&amp;mode=hide
  [8]: http://docs.jboss.org/hibernate/orm/4.3/topical/html/logging/Logging.html

How do you configure logging in Hibernate 4 to use SLF4J

Why one would use one of the following packages instead of the other?

  - Java Logging
  - Commons Logging
  - Log4j
  - SLF4j
  - Logback


What&#39;s Up with Logging in Java?

I&#39;m building a small Java app and hoping to use logback for logging.

My app has a dependency on an older project that does its logging via 

    org.apache.commons | com.springsource.org.apache.commons.logging | 1.1.1

...so my plan was to use 

    org.slf4j | jcl-over-slf4j | 1.5.6

...to redirect the JCL logging to 

    org.slf4j | slf4j-api | 1.6.0

...and ultimately to 

    ch.qos.logback | logback-classic | 0.9.22
    ch.qos.logback | logback-core | 0.9.22

so my app can log through logback via its slf4j API while the old library code can log into the same location via the redirection.

Alas, this results in 

    java.lang.NoSuchMethodError: org.slf4j.spi.LocationAwareLogger.log(Lorg/slf4j/Marker;Ljava/lang/String;ILjava/lang/String;Ljava/lang/Throwable;)V
	at   org.apache.commons.logging.impl.SLF4JLocationAwareLog.info(SLF4JLocationAwareLog.java:141)

I&#39;ve tried higher and lower verision numbers on some of these jars and also digging through API documentation and such... but I&#39;m unable to find and solve the problem. 

Help, please?

Although logback is considered the &quot;strategic&quot; logging framework, I have some leeway in which logging mechanism I ultimately use. I&#39;d hope to use either logback or log4j, though, and I definitely want to merge the old project&#39;s logging into whatever the &quot;new&quot; logging framework ends up being, via a common configuration.

Logging framework incompatibility

Is it possible to somehow intercept the logging (SLF4J + logback) and get an `InputStream` (or something else that is readable) via a JUnit test case...?

How to intercept SLF4J (with logback) logging via a JUnit test?

What&#39;s the correct approach to log both an error message and an exception using [SLF4J][1]?

I&#39;ve tried doing this but the exception stack trace is never printed:

`logger.error(&quot;Unable to parse data {}&quot;, inputMessage, e);`

In this case I want to populate `{}` with the `inputMessage` as well as logging out the exception stacktrace.

The only way I can see to do this would be to do this:

`logger.error(&quot;Unable to parse data &quot; + inputMessage, e);`

which is not pretty.


  [1]: http://www.slf4j.org/

How to log exception and message with placeholders with SLF4J

I have an existing application which does all of its logging against log4j. We use a number of other libraries that either also use log4j, or log against Commons Logging, which ends up using log4j under the covers in our environment. One of our dependencies even logs against slf4j, which also works fine since it eventually delegates to log4j as well.

Now, I&#39;d like to add ehcache to this application for some caching needs. Previous versions of ehcache used commons-logging, which would have worked perfectly in this scenario, but as of [version 1.6-beta1][1] they have removed the dependency on commons-logging and replaced it with java.util.logging instead.

Not really being familiar with the built-in JDK logging available with java.util.logging, is there an easy way to have any log messages sent to JUL logged against log4j, so I can use my existing configuration and set up for any logging coming from ehcache?

Looking at the javadocs for JUL, it looks like I could set up a bunch of environment variables to change which `LogManager` implementation is used, and perhaps use that to wrap log4j `Logger`s in the JUL `Logger` class. Is this the correct approach?

Kind of ironic that a library&#39;s use of built-in JDK logging would cause such a headache when (most of) the rest of the world is using 3rd party libraries instead.


  [1]: http://ehcache.sourceforge.net/changes-report.html#1.6.0-beta1

How to send java.util.logging to log4j?

I am little bit confused by these three logger libraries. It seems like that they can do the similar thing in Java logging...

What is the difference between Log4j, SLF4J and Logback?

For the first time in my life I find myself in a position where I&#39;m writing a Java API that will be open sourced. Hopefully to be included in many other projects.

For logging I (and indeed the people I work with) have always used JUL (`java.util.logging`) and never had any issues with it. However now I need to understand in more detail what I should do for my API development. I&#39;ve done some research on this and with the information I&#39;ve got I just get more confused. Hence this post.

Since I come from JUL I&#39;m biased on that. My knowledge of the rest is not that big.

From the research I&#39;ve done I&#39;ve come up with these reasons why people do not like JUL:

1. *&quot;I started developing in Java long before Sun released JUL and it was just easier for me to continue with logging-framework-X rather than to learn something new&quot;*. Hmm. I&#39;m not kidding, this is actually what people say. With this argument we could all be doing COBOL. (however I can certainly relate to this being a lazy dude myself)

2. *&quot;I don&#39;t like the names of the logging levels in JUL&quot;*. Ok, seriously, this is just not enough of a reason to introduce a new dependency.

3. *&quot;I don&#39;t like the standard format of the output from JUL&quot;*. Hmm. This is just configuration. You do not even have to do anything code-wise. (true, back in old days you may have had to create your own Formatter class to get it right).

4. *&quot;I use other libraries that also use logging-framework-X so I thought it easier just to use that one&quot;*. This is a circular argument, isn&#39;t ? Why does &#39;everybody&#39; use logging-framework-X and not JUL?

5. *&quot;Everybody else is using logging-framework-X&quot;*. This to me is just a special case of the above. Majority is not always right.


So the real big question is **why not JUL?**. What is it I have missed ? The raison d&#39;&#234;tre for logging facades (SLF4J, JCL) is that multiple logging implementations have existed historically and the reason for that really goes back to the era before JUL as I see it. If JUL was perfect then logging facades wouldn&#39;t exist, or what? To make matters more confusing JUL is to some extent a facade itself, allowing Handlers, Formatters and even the LogManager to be swapped. 

Rather than embracing multiple ways of doing the same thing (logging), shouldn&#39;t we question why they were necessary in the first place? (and see if those reasons still exist)

Ok, my research so far has led to a couple of things that I can see may be **real issues** with JUL:

1. **Performance**. Some say that performance in SLF4J is superior to the rest. This seems to me to be a case of premature optimization. If you need to log hundreds of megabytes per second then I&#39;m not sure you are on the right path anyway. JUL has also evolved and the tests you did on Java 1.4 may no longer be true. You can read about it [here][1] and this fix has made it into Java 7. Many also talk about the overhead of string concatenation in logging methods. However template based logging avoids this cost and it exist also in JUL. Personally I never really write template based logging. Too lazy for that. For example if I do this with JUL:

        log.finest(&quot;Lookup request from username=&quot; + username 
           + &quot;, valueX=&quot; + valueX
           + &quot;, valueY=&quot; + valueY));

    my IDE will warn me and ask permission that it should change it to:

        log.log(Level.FINEST, &quot;Lookup request from username={0}, valueX={1}, valueY={2}&quot;, 
           new Object[]{username, valueX, valueY});

    .. which I will of course accept. Permission granted ! Thank you for your help.

    So I don&#39;t actually write such statements myself, that is done by the IDE.

    In conclusion on the issue of performance I haven&#39;t found anything that would suggest that JUL&#39;s performance is not ok compared to the competition.


2. **Configuration from classpath**. Out-of-the-box JUL cannot load a configuration file from the classpath. It is a [few lines of code][2] to make it do so. I can see why this may be annoying but the solution is short and simple.


3. **Availability of output handlers**. JUL comes with 5 output handlers out-of-the-box: console, file stream, socket and memory. These can be extended or new ones can be written. This may for example be writing to UNIX/Linux Syslog and Windows Event Log. I have personally never had this requirement nor have I seen it used but I can certainly relate to why it may be a useful feature. Logback comes with an appender for Syslog for example. Still I would argue that
    1. 99.5% of the needs for output destinations are covered by what is in JUL out-of-the-box.
    2. Special needs could be catered for by custom handlers on top of JUL rather than on top of something else. There&#39;s nothing to me that suggests that it takes more time to write a Syslog output handler for JUL than it does for another logging framework.


I&#39;m really concerned that there&#39;s something I&#39;ve overlooked. The use of logging facades  and logging implementations other than JUL is so widespread that I have to come to the conclusion that it&#39;s me who just doesn&#39;t understand. That wouldn&#39;t be the first time, I&#39;m afraid. :-)

So what should I do with my API?  I want it to become successful.  I can of course just &quot;go with the flow&quot; and implement SLF4J (which seems the most popular these days) but for my own sake I still need to understand exactly what is wrong with the JUL of today that warrants all the fuzz?  Will I sabotage myself by choosing JUL for my library ?


## Testing performance 
*(section added by nolan600 on 07-JUL-2012)*

There&#39;s a reference below from Ceki about SLF4J&#39;s parametrization being 10 times or more faster than JUL&#39;s. So I&#39;ve started doing some simple tests. At first glance the claim is certainly correct. Here are the preliminary results (but read on!):

* Execution time SLF4J, backend Logback: 1515
* Execution time SLF4J, backend JUL: 12938
* Execution time JUL: 16911

The numbers above are msecs so less is better. So 10 times performance difference is by first actually pretty close. My initial reaction: That is a lot !

Here is the core of the test. As can be seen an integer and a string is construted in a loop which is then used in the log statement:

        for (int i = 0; i &lt; noOfExecutions; i++) {
            for (char x=32; x&lt;88; x++) {
                String someString = Character.toString(x);
                // here we log 
            }
        }


(I wanted the log statement to have both a primitive data type (in this case an int) and a more complex data type (in this case a String). Not sure it matters but there you have it.)


The log statement for SLF4J:

    logger.info(&quot;Logging {} and {} &quot;, i, someString);

The log statement for JUL:

    logger.log(Level.INFO, &quot;Logging {0} and {1}&quot;, new Object[]{i, someString});
 

The JVM was &#39;warmed up&#39; with the same test executed once before the actual measurement was done. Java 1.7.03 was used on Windows 7. Latest versions of SLF4J (v1.6.6) and Logback (v1.0.6) was used. Stdout and stderr was redirected to null device.

However, careful now, it turns out JUL is spending most of its time in `getSourceClassName()` because JUL by default prints the source class name in the output, while Logback doesn&#39;t. So we are comparing apples and oranges. I have to do the test again and configure the logging implementations in a similar manner so that they actually output the same stuff. I do however suspect that SLF4J+Logback will still come out on top but far from the initial numbers as given above. Stay tuned.

Btw: The test was first time I&#39;ve actually worked with SLF4J or Logback. A pleasant experience. JUL is certainly a lot less welcoming when you are starting out.

## Testing performance (part 2)

*(section added by nolan600 on 08-JUL-2012)*

As it turns out it doesn&#39;t really matter for performance how you configure your pattern in JUL, i.e. whether or not it includes the source name or not. I tried with a very simple pattern:

    java.util.logging.SimpleFormatter.format=&quot;%4$s: %5$s [%1$tc]%n&quot;

and that did not change the above timings at all. My profiler revealed that the logger still spent a lot of time in calls to `getSourceClassName()` even if this was not part of my pattern. The pattern doesn&#39;t matter.

I&#39;m therefore concluding on the issue of performance that at least for the tested template based log statement there seems to be roughly a factor of 10 in real performance difference between JUL (slow) and SLF4J+Logback (quick). Just like Ceki said.

I can also see another thing namely that SLF4J&#39;s `getLogger()` call is a lot more expensive than JUL&#39;s ditto. (95 ms vs 0.3 ms if my profiler is accurate). This makes sense. SLF4J has to do some time on the binding of the underlying logging implementation. This doesn&#39;t scare me. These calls should be somewhat rare in the lifetime of an application. The fastness should be in the actual log calls.


# Final conclusion

*(section added by nolan600 on 08-JUL-2012)*

Thank you for all your answers. Contrary to what I initially thought I&#39;ve ended up deciding to use SLF4J for my API. This is based on a number of things and your input:

1. It gives flexibility to choose log implementation at deployment time.

2. Issues with lack of flexibility of JUL&#39;s configuration when run inside an application server.

3. SLF4J is certainly a lot faster as detailed above in particular if you couple it with Logback. Even if this was just a rough test I have reason to believe that a lot more effort has gone into optimization on SLF4J+Logback than on JUL.

4. Documentation. The documentation for SLF4J is simply a lot more comprehensive and precise.

5. Pattern flexibility. As I did the tests I set out to have JUL mimic the default pattern from Logback. This pattern includes the name of the thread. It turns out JUL cannot do this out of the box. Ok, I haven&#39;t missed it until now, but I don&#39;t think it is a thing that should be missing from a log framework. Period! 

6. Most (or many) Java projects today use Maven so adding a dependency is not that big a thing especially if that dependency is rather stable, i.e. doesn&#39;t constantly change its API. This seems to be true for SLF4J. Also the SLF4J jar and friends are small in size.

So the strange thing that happened was that I actually got quite upset with JUL after having worked a bit with SLF4J. I still regret that it has to be this way with JUL. JUL is far from perfect but kind of does the job. Just not quite well enough. The same can be said about `Properties` as an example but we do not think about abstracting that so people can plug in their own configuration library and what have you. I think the reason is that `Properties` comes in just above the bar while the opposite is true for JUL of today ... and in the past it came in at zero because it didn&#39;t exist.


  [1]: http://jeremymanson.blogspot.dk/2009/04/faster-logging-with-faster-logger.html
  [2]: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4958543

Why not use java.util.logging?

I&#39;m currently observing that a 3rd party library (namely restfb) is using java.util.logging and I&#39;m seeing those logs end up in STDOUT even though I don&#39;t have an SLF4J console appender configured in my logback.xml. I also have the [jul-to-slf4j][1] bridge in my classpath. Does the jul-to-slf4j bridge only log to the appenders configured by logback when the bridge is installed or does it also log to stdout?


  [1]: http://www.slf4j.org/images/legacy.png

JUL to SLF4J Bridge

What&#39;s the difference between slf4j-log4j12 and [log4j-over-slf4j][1] and when should each be used?

&lt;!-- language: lang-xml --&gt;

    &lt;dependency&gt;
    	&lt;groupId&gt;org.slf4j&lt;/groupId&gt;
    	&lt;artifactId&gt;slf4j-log4j12&lt;/artifactId&gt;
    	&lt;version&gt;1.7.12&lt;/version&gt;
    &lt;/dependency&gt;
    &lt;dependency&gt;
    	&lt;groupId&gt;org.slf4j&lt;/groupId&gt;
    	&lt;artifactId&gt;log4j-over-slf4j&lt;/artifactId&gt;
    	&lt;version&gt;1.7.12&lt;/version&gt;
    &lt;/dependency&gt;


  [1]: https://www.slf4j.org/legacy.html#log4j-over-slf4j

Difference between slf4j-log4j12 and log4j-over-slf4j

I have the followed imports:

    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;

and the following instantiation:

    private static Logger logger = LoggerFactory.getLogger(Test.class);

and the following in my Main method:

    logger.info(&quot;SOME MESSAGE: &quot;);

However, I&#39;m not able to find the output anywhere. All I see is that in my console there is:

    21:21:24.235 [main] INFO  some_folder.Test - SOME MESSAGE: 

How do I locate the log file?

Note that the following are on my  build path:

`slf4j-api-1.7.5.jar`

`slf4j-log4j12-1.6.4.jar`

I read the answer to similar questions but nobody actually says how to fix the problem.


Where does the slf4j log file get saved?

I use Spring Boot and want it to write log output to a file.

According to the docs, this is simply done by setting

    logging.file=filename.log

While the console output works fine, `filename.log` is not created. Also, if I create the file manually, nothing is written to it. What do I miss?

Spring Boot - no log file written (logging.file is not respected)

I have the following Logger I want to mock out, but to validate log entries are getting called, not for the content.

	private static Logger logger = 
			LoggerFactory.getLogger(GoodbyeController.class);

I want to Mock ANY class that is used for LoggerFactory.getLogger() but I could not find out how to do that.
This is what I ended up with so far:

	@Before
	public void performBeforeEachTest() {
		PowerMockito.mockStatic(LoggerFactory.class);
		when(LoggerFactory.getLogger(GoodbyeController.class)).
			thenReturn(loggerMock);

		when(loggerMock.isDebugEnabled()).thenReturn(true);
		doNothing().when(loggerMock).error(any(String.class));

		...
	}

I would like to know:

1. Can I Mock the static `LoggerFactory.getLogger()` to work for any class?
2. I can only seem to run `when(loggerMock.isDebugEnabled()).thenReturn(true);` in the `@Before` and thus I cannot seem to change the characteristics per method. Is there a way around this?


----------


**Edit findings:**


I thought I tried this already and it didnt work:

     when(LoggerFactory.getLogger(any(Class.class))).thenReturn(loggerMock);
	 
But thank you, as it did work.

However I have tried countless variations to:

    when(loggerMock.isDebugEnabled()).thenReturn(true);

I cannot get the loggerMock to change its behavior outside of `@Before` but this only happens with Coburtura. With Clover, the coverage shows 100% but there is still an issue either way.

I have this simple class:

    public ExampleService{
        private static final Logger logger =
                LoggerFactory.getLogger(ExampleService.class);
		
        public String getMessage() {		
		if(logger.isDebugEnabled()){
			logger.debug(&quot;isDebugEnabled&quot;);
			logger.debug(&quot;isDebugEnabled&quot;);
		}
		return &quot;Hello world!&quot;;
        }
        ...
    }
	
Then I have this test:

	
	@RunWith(PowerMockRunner.class)
	@PrepareForTest({LoggerFactory.class})
	public class ExampleServiceTests {

		@Mock
		private Logger loggerMock;
		private ExampleServiceservice = new ExampleService();
			
		@Before
		public void performBeforeEachTest() {
			PowerMockito.mockStatic(LoggerFactory.class);
			when(LoggerFactory.getLogger(any(Class.class))).
				thenReturn(loggerMock);
				
			//PowerMockito.verifyStatic(); // fails
		}

		@Test
		public void testIsDebugEnabled_True() throws Exception {
			when(loggerMock.isDebugEnabled()).thenReturn(true);
			doNothing().when(loggerMock).debug(any(String.class));
				
			assertThat(service.getMessage(), is(&quot;Hello null: 0&quot;));
			//verify(loggerMock, atLeast(1)).isDebugEnabled(); // fails
		}

		@Test
		public void testIsDebugEnabled_False() throws Exception {
			when(loggerMock.isDebugEnabled()).thenReturn(false);
			doNothing().when(loggerMock).debug(any(String.class));
				
			assertThat(service.getMessage(), is(&quot;Hello null: 0&quot;));
			//verify(loggerMock, atLeast(1)).isDebugEnabled(); // fails
		}
	}

In clover I show 100% coverage of the `if(logger.isDebugEnabled()){` block.
But if I try to verify the `loggerMock`:

	verify(loggerMock, atLeast(1)).isDebugEnabled();

I get zero interactions.
I also tried `PowerMockito.verifyStatic()`; in `@Before` but that also has zero interactions.

This just seems strange that Cobertura shows the `if(logger.isDebugEnabled()){` as being not 100% complete, and Clover does, but both agree the verification fails.

Mocking Logger and LoggerFactory with PowerMock and Mockito

Im using slf4j for tracing the information. My code is

    private static final Logger log = LoggerFactory.getLogger(ObjectTest.class);
    
    log.trace(&quot;Time taken to store &quot; + count
                + &quot; objects of size &quot; + size +  &quot; is &quot; + (time) + &quot; msecs&quot;);
    
    log.trace(&quot;Time taken to store {} objects of size {} is {} msecs&quot;,
            new Object[] { count, size, time });
    
    log.trace(&quot;Time taken to store {} objects of size {} is {} msecs&quot;,
            count, size, time);

Which would be the preferred mechanism to log traces.


Is there a correct way to pass arguments in slf4j?

I&#39;m using slf4j and I want to unit test my code to make sure that warn/error log messages are generated under certain conditions. I&#39;d rather these be strict unit tests, so I&#39;d prefer not to have to pull up logging configuration from a file in order to test that the log messages are generated. The mocking framework I&#39;m using is Mockito.

What is the best way to unit-test SLF4J log messages?

The stacktraces are truncated - e.g. they end with `[info]   ...`

Using `last` or changing `traceLevel` doesn&#39;t help - it simply prints the complete stacktrace of the sbt wrapper.

This is testing with testng (also I believe using scalatest and sl4j)

How can I get complete stacktraces for exceptions thrown in tests when using sbt and testng?

How to globally enable `debug` for all the `slf4j.Logger` objects?

All Slf4j Solutions on Gang of Coders

Total of 38 Slf4j Solutions