how can I rectify the method error while using Log4j API in java class?

Question

I am new to Log4j API. So, I configured the properties file and written the sample program to test it. Below is my config file and test class.

< ?xml version="1.0" encoding="UTF-8" ?>
<!--<span class="hiddenSpellError" pre=""-->DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
xmlns:log4j="http://jakarta.apache.org/log4j/">

<appender name="console" class="org.apache.log4j.ConsoleAppender">
<param name="Target" value="System.out"/>
<layout class="org.apache.log4j.PatternLayout">
    -5p %c %x - %m%n"/>
</layout>
</appender>

<appender name="fileAppender" class="org.apache.log4j.RollingFileAppender">
<param name="File" value="./logs/testlog.log"/>
<layout class="org.apache.log4j.PatternLayout">
-5p %c %p - %m%n"/>
</layout>
</appender>

<root>
<priority value ="trace"></priority>
<appender-ref ref="console"></appender>
<appender-ref ref="fileAppender"></appender>
</root>
</log4j:configuration>

and sample test class is

public class Log4jExample {
private static Logger logger=Logger.getLogger("Project_name");
public static void main(String[] args){
try{
  FileInputStream fstream = 
                     new FileInputStream("D:\\textfile.txt");
  // use DataInputStream to read binary NOT text
  // DataInputStream in = new DataInputStream(fstream);
  BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
  String strLine;
  while ((strLine = br.readLine()) != null){
 System.out.println (strLine);
  }
  in.close();
 }catch (FileNotFoundException fe){
 logger.error("File Not Found",fe);
    logger.warn("This is a warning message");
    logger.trace("This message will not be logged since log level is set as DEBUG");
 }catch (IOException e){
 logger.error("IOEXception occured:", e);
}
}

}

am working in netbeans and it is showing that logger.error,logger.trace,logger.warn are "cannot file symbol" error. Please advice with this issue.

am receiving this error. java.lang.NoClassDefFoundError: org/slf4j/ILoggerFactory — Mahes_sa_jey
– Mahes_sa_jey, Commented Dec 11, 2013 at 12:44

Kai Sternad · Accepted Answer · 2013-12-11 11:54:50Z

0

Make sure you have Log4j in your classpath and your code compiles. Also make sure your configuration file is correct. The file you posted is invalid xml. Take a look at the Log4j xml format documentation. Here is syntactically corrected version:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

    <appender name="console" class="org.apache.log4j.ConsoleAppender">
        <param name="Target" value="System.out"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="-5p %c %x - %m%n"/>
        </layout>
    </appender>

    <appender name="fileAppender" class="org.apache.log4j.RollingFileAppender">
        <param name="File" value="./logs/testlog.log"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="-5p %c %p - %m%n"/>
        </layout>
    </appender>

    <root>
        <priority value="trace"/>
        <appender-ref ref="console"/>
        <appender-ref ref="fileAppender"/>
    </root>
</log4j:configuration>

answered Dec 11, 2013 at 11:54

Kai Sternad

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2 Comments

Mahes_sa_jey Over a year ago

am receiving java.lang.NoClassDefFoundError: org/slf4j/ILoggerFactory error

Kai Sternad Over a year ago

This indicates that you are using slf4j. Make sure you have it in the classpath.

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