Using log4j how to print System.out.println statements in logfile

Question

I am learning log4j still and I facing this problem.

As in my current example I not able to print System.out.println statements in logfiles.

I have gone through other question and answers in the Stack Overflow and it is a duplicate question, but I still did not understand those.

Below is Java class

public class Testing
{
private final static Logger logger = Logger.getLogger(Testing.class);
static
{
    PropertyConfigurator.configure("log4j.properties");
}
public static void main(String args[])
{
    System.out.println("Entered main method...............");
    logger.error("An error has occurred might");
}
}

log4j.properties file:

log4j.rootLogger=DEBUG, file, console

log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.File=logs/justfortesting.log
log4j.appender.file.Append=true
log4j.appender.file.ImmediateFlush=true   
log4j.appender.FILE.filter.b=org.apache.log4j.varia.LevelMatchFilter    
log4j.appender.FILE.filter.b.LevelToMatch=ERROR    
log4j.appender.FILE.filter.b.AcceptOnMatch=false 
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d %d{Z} [%t] %-5p (%F:%L) - %m%n

log4j.logger.com.log4j=DEBUG, file, console

log4j.additivity.com.log4j=false

So anyone suggest, what I need to change/add new things to this??

Answer 1

System.out.println() writes to the standard output. If you want write these messages to the log, you'll have to call the logger methods:

public static void main(String args[])
{
  logger.info("Entered main method...............");
  logger.error("An error has occurred might");
}

Answer 2

I got the solution for above problem, by modifying my Testing class and added one new class with the existing code.

public class Testing
{
private final static Logger logger = Logger.getLogger(Testing.class);
static
{
    PropertyConfigurator.configure("log4j.properties");
}
public static void main(String args[])
{
    Logger out = Logger.getLogger("SystemOut");
    Level info = Level.INFO;
    System.setOut(new PrintStream(new LoggingOutputStream(out, info),true));
    System.out.println("Entered main method...............");
    System.out.println("Printing 2nd...............");
}
}

Added LoggingOutputStream class for printing System.out.println statements in logfiles.