java - How to use log4j to log different package's message into same log file? -

i beginner using log4j, please don't mind stupid questions.

now have jar contain methods use in different classes. let calculator method. method has several messages , exception handling need log.

i have 2 classes need use method calculation , these 2 classes have own log file. classa.log , classb.log

the question how log message , error came calculator in classa.log , classb.log depends on class calling calculator.

i want classa.log , classb.log like:

[datetime] info - [foo.a] class [datetime] info - [foo.a] calling calculator [datetime] info - [cal.mycal.calculator] enter calculator , start calculating [datetime] warn - [cal.mycal.calculator] warning message calculator [datetime] error - [cal.mycal.calculator] error message calculator [datetime] info - [foo.a] mistakes made. [datetime] info - [foo.a] class done 

in log4j.xml, need add logger , ref class need log

  <logger name="foo.a">     <level value="info" />     <appender-ref ref="a" />   </logger>    <logger name="cal.mycal.calculator">     <level value="info" />     <appender-ref ref="a" />   </logger> 

and appender

  <appender name="a" class="org.apache.log4j.dailyrollingfileappender">     <param name="file" value="log/classa.log"/>     <param name="datepattern" value="'.'yyyy-mm-dd"></param>     <param name="append" value="true"/>     <layout class="org.apache.log4j.patternlayout">       <param name="conversionpattern" value="[%d{dd-mmm-yyyy hh:mm:ss}] %-5p - [%c] %m%n"/>     </layout>   </appender> 

but after doing this, method call foo.b won't write classb.log. message calculator write classa.log

how logger:

protected final log log = logfactory.getlog(getclass()); 

can have suggestions? thank you.