java - NoSuchMethodError: org/apache/log4j/Logger.setLevel(Lorg/apache/log4j/Level;) -

i using these log4j, slf4j , ch.qos.logback dependencies in pom.xml of java project:

        <dependency>             <groupid>org.slf4j</groupid>             <artifactid>slf4j-api</artifactid>             <version>1.6.4</version>         </dependency>         <dependency>             <groupid>ch.qos.logback</groupid>             <artifactid>logback-core</artifactid>             <version>1.1.2</version>         </dependency>             <dependency>             <groupid>org.slf4j</groupid>             <artifactid>jcl-over-slf4j</artifactid>             <version>1.6.4</version>         </dependency>         <dependency>             <groupid>org.slf4j</groupid>             <artifactid>log4j-over-slf4j</artifactid>             <version>1.6.4</version>         </dependency>         <dependency>             <groupid>org.slf4j</groupid>             <artifactid>jul-to-slf4j</artifactid>             <version>1.6.4</version>         </dependency>         <dependency>             <groupid>log4j</groupid>             <artifactid>log4j</artifactid>             <version>1.2.14</version>         </dependency> 

i wanted use external servlet library , defined dependency in pom. init method of servlet looks this:

import org.apache.log4j.level; import org.apache.log4j.logger;  ....  public class healthpageservlet extends httpservlet{     private static final long serialversionuid = 1l;     private final logger logger = logger.getlogger(healthpageservlet.class.getname());      protected healthpageservice service;       public static final string version = "healthpage-version 0.0.4";      public void init() throws servletexception {         logger.setlevel(level.info);         .....     } 

my weblogic server shows me exception init method, when start server:

java.lang.nosuchmethoderror: org/apache/log4j/logger.setlevel(lorg/apache/log4j/level;)v

when in eclipse open healthpageservlet jar content, has log4j-1.2.15 jar inside web-inf/lib folder. if exclude dependency pom.xml, see exception , server not start. problem?

since log4j version (1.2.15) of external jar incompatible slf4j version (1.6.4) of parent project (where logger.setlevel() not available), had update slf4j version 1.7.7.