Question

Okay so I’m trying to make a memory appender (simply a logger, that logs to an ArrayList instead of the console or to a file) but for now I want to disable it from printing to the console.

The questions and websites, I’ve read so far (but I still cant figure it out is)..

• StackOverFlow Question log4j: Log output of a specific class to a specific appender
  
• StackOverFlow Question log4j : Disable log4j console logging and enable file logging
  
• Coder Launch: log4j: stop logging to console

It has all the segments on what I’m trying to achieve, but I’m still kind of confused.

I also read this segment from Logback or Log4j Additivity Explained Which states..

If the aditivity flag of logger X however is set to false, or disabled, then calling x.debug() will only log to the file.

So in theory my log4j.properties file

log4j.rootLogger=ERROR, console
log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=%d %5p %c (%F:%L) - %m%n
#hide the Log4jMemoryAppender from console
log4j.logger.nz.ac.massey.cs.sdc.log4jassignment.s06005586.MemoryAppender= ERROR, MEMORY_APPENDER
log4j.appender.MEMORY_APPENDER=nz.ac.massey.cs.sdc.log4jassignment.s06005586.MemoryAppender.Log4jMemoryAppender
log4j.additivity.rootLogger = false
log4j.additivity.console = false
log4j.additivity.MEMORY_APPENDER=false

Should only print ***Hello World and exclude anything else from the MEMORY_APPENDER, rootLogger and console.

package nz.ac.massey.cs.sdc.log4jassignment.s06005586.MemoryAppender;

import java.util.ArrayList;
import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.spi.LoggingEvent;

import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;

public class Log4jMemoryAppender extends AppenderSkeleton {

ArrayList<LoggingEvent> eventsList = new ArrayList();

public static void main (String [] args) {

    PropertyConfigurator.configure("Lib/log4j.properties");
    Log4jMemoryAppender app = new Log4jMemoryAppender();
    Logger logger = Logger.getLogger(Log4jMemoryAppender.class);
    logger.setLevel(Level.INFO);

    logger.addAppender(app);
    logger.info("Hello World");
    logger.debug("Level DEBUG Is SET");

    for (LoggingEvent le: app.eventsList) {
        System.out.println("***" + le.getMessage());
    }
} 

@Override
protected void append(LoggingEvent event) {
    eventsList.add(event);
}

public void close() {
}

public boolean requiresLayout() {
    return false;
}
}

But it doesn’t…

_{(source: iforce.co.nz)}

Answer 1

The line

MEMORY_APPENDER=false

will not work, you cannot set an appender to have the value false.

In you case better do something like this:

log4j.rootLogger=ERROR, console
log4j.appender.console=org.apache.log4j.ConsoleAppender

log4j.logger.nz.ac.massey.cs.sdc.log4jassignment.s06005586.MemoryAppender = ERROR, MEMORY_APPENDER
log4j.additivity.nz.ac.massey.cs.sdc.log4jassignment.s06005586.MemoryAppender = false

The Logger being used in one of your example is nz.ac.massey.cs.sdc.log4jassignment.s06005586.MemoryAppender and that should map to a logger in the log4j.properties or just the package part like nz.ac.massey.cs.sdc.log4jassignment.

---

It seems like you are mixing a lot here. Is Log4jMemoryAppender your MEMORY_APPENDER or not?

And why are you calling BasicConfigurator.configure()? Don’t you want to use the log4j.properties?

---

Normally in a class you do this to get a logger:

package com.mycompany;

public class MyClass {
    private static final Logger log = Logger.getLogger(MyClass.class);
    ...
}

The logger name will be the fully qualified classname com.mycompany.MyClass.

Then you can have a log4j.properties like this:

log4j.rootLogger=ERROR, console
log4j.appender.console=org.apache.log4j.ConsoleAppender

log4j.logger.com.mycompany=INFO, file
log4j.additivity.com.mycompany=false

logfj.appender.file = <some file appender>

---

OK, starting from beginning. A very simple example.

src/main/java/Log4JTest.java

package org.stackoverflow;

import org.apache.log4j.Logger;

/**
 * @author maba, 2012-08-22
 */
public class Log4JTest {

    public static final Logger log = Logger.getLogger(Log4JTest.class);

    public static void main(String[] args) {
        log.error("Error in main");
    }
}

src/main/resources/log4j.properties

log4j.rootLogger = ERROR, console

log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n

Now compile and make sure that log4j.properties is in your classpath together with the log4j.jar and your own classes when running.

You will see this:

0    [main] ERROR org.stackoverflow.Log4JTest  - Error in main

From here you can try to add a file appender or your own memory appender.