ClassNotFoundException: org.slf4j.LoggerFactory

Question

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 ?

try to extract the jar and see if it contains \org\slf4j\LoggerFactory. — Umer Hayat, Jan 27 '12 at 07:18
You don't need to just download the jar, you must also put it in your classpath when compiling and running your code. Did you do that? — Jesper, Jan 27 '12 at 07:57

score 74 · Answer 1 · edited Apr 10 '15 at 09:02

Better to always download as your first try, the most recent version from the developer's site

I had the same error message you had, and by downloading the jar from the above (slf4j-1.7.2.tar.gz most recent version as of 2012OCT13), untarring, uncompressing, adding 2 jars to build path in eclipse (or adding to classpath in comand line):

slf4j-api-1.7.2.jar
slf4j-simple-1.7.2.jar

I was able to run my program.

gprathour · Accepted Answer · 2019-11-21T10:47:50.230

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Try downloading jar from here

You can find, it holds the class you need.

EDIT

Seems like the website has changed its structure. You need to choose which jar file you need for your project.

For slf4j-api jar file for latest version as of now, please visit this link

For slf4j-simple jar file for latest version as of now, please visit this link

edited Nov 21 '19 at 10:47

answered Jan 27 '12 at 07:16

gprathour

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Thanks , error gone , now it says NoClassDefFoundError: org/slf4j/impl/StaticLoggerBinder Any idea – junaidp Jan 27 '12 at 07:29
get from here http://www.java2s.com/Code/Jar/STUVWXYZ/Downloadslf4jlog4j12156jar.htm – gprathour Jan 27 '12 at 07:30
java.lang.IllegalAccessError: tried to access field org.slf4j.impl.StaticLoggerBinder.SINGLETON from class org.slf4j.LoggerFactory – junaidp Jan 27 '12 at 07:39
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I tried to visit: http://www.java2s.com/Code/Jar/STUVWXYZ/Downloadslf4japi131jar.htm But, I found the error as: Not Found The requested document was not found on this server. – Ripon Al Wasim Jan 03 '13 at 05:32
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The given [url](http://www.java2s.com/Code/Jar/STUVWXYZ/Downloadslf4japi131jar.htm) is not working now, it says __The requested document was not found on this server__. Please update the link – Visruth Feb 05 '13 at 05:34
In which of the 21 folders? – clankill3r Nov 21 '19 at 10:26
@gprathour Damn your fast :) – clankill3r Nov 21 '19 at 10:58

score 7 · Answer 3 · edited Jun 20 '20 at 09:12

i know this is an old Question , but i faced this problem recently and i looked for it in google , and i came across this documentation here from slf4j website .

as it describes the following :

This error is reported when the org.slf4j.impl.StaticLoggerBinder class could not be loaded into memory. This happens when no appropriate SLF4J binding could be found on the class path.

Placing one (and only one) of slf4j-nop.jar, slf4j-simple.jar, slf4j-log4j12.jar, slf4j-jdk14.jar or logback-classic.jar on the class path should solve the problem.

SINCE 1.6.0 As of SLF4J version 1.6, in the absence of a binding, SLF4J will default to a no-operation (NOP) logger implementation.

Hope that will help someone .

score 3 · Answer 4 · answered Jan 23 '15 at 19:41

For a bit more explanation: keep in mind that the "I" in "api" is interface. The slf4j-api jar only holds the needed interfaces (actually LoggerFactory is an abstract class). You also need the actual implementations (an example of which, as noted above, can be found in slf4j-simple). If you look in the jar, you'll find the required classes under the "org.slf4j.impl" package.

score 2 · Answer 5 · answered Mar 19 '13 at 12:27

You'll need to download SLF4J's jars from the official site as either a zip (v1.7.4) or tar.gz (v1.7.4)

The download contains multiple jars based on how you want to use SLF4J. If you're simply trying to resolve the requirement of some other library (GWT, I assume) and don't really care about using SLF4J correctly, then I would probably pick the slf4j-api-1.7.4.jar since the Simple jar suggested by another answer does not contain, to my knowledge, the specific class you're looking for.

score 2 · Answer 6 · answered Sep 20 '19 at 09:45

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add this dependency https://mvnrepository.com/artifact/org.slf4j/slf4j-api/1.7.28

will help fix error

answered Sep 20 '19 at 09:45

Vy Do

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score 1 · Answer 7 · edited Feb 13 '17 at 20:56

I got this problem too and I fixed it in this way. I was trying to run mapreduce job locally through Eclipse, after set the configurations, I met this error (in Linux, Virtual Box) To solve it,

right click on the project you want to run,
go "Properties"->"Java Build Path"->"Add External Jars",
then go to file:/usr/lib/Hadoop/client-0.20, choose the three jars named started by "slf4j".

Then you'll be able to run the job locally. Hope my experience will help someone.

score 1 · Answer 8 · edited Mar 04 '19 at 20:15

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Add the following JARs to the build path or lib folder of the project:

edited Mar 04 '19 at 20:15

tarta

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answered Jul 25 '18 at 07:23

Shanu Shine

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score 0 · Answer 9 · answered Jan 03 '13 at 05:42

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It needs "slf4j-simple-1.7.2.jar" to resolve the problem.

I downloaded a zip file "slf4j-1.7.2.zip" from http://slf4j.org/download.html. I extracted the zip file and i got slf4j-simple-1.7.2.jar

answered Jan 03 '13 at 05:42

Ripon Al Wasim

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You can also download "slf4j-1.7.2.tar.gz" from the same URL mentioned in my above answer – Ripon Al Wasim Jan 03 '13 at 05:43

score 0 · Answer 10 · answered Feb 20 '14 at 12:21

I had the same on Android. This is how i fixed it:

including ONLY the file:

slf4j-api-1.7.6.jar

in my libs/ folder

Having any additional slf4j* file, caused the NoClassDefFoundError.

Obviously, the rest of the libs can be there (android-support-v4, etc)

Versions: Eclipse Kepler 2013 06 14 - 02 29 ADT 22.3 Android SDK: 4.4.2

Hope someone saves the time i wasted thanks to this!

ClassNotFoundException: org.slf4j.LoggerFactory

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