Java – Initializing log4j for a stand alone application

javalog4jlogging

I'm a newbie to log4j. This is what I have . I have about 20 files in different packages in a STAND ALONE JAVA APPLICATION.
I am trying to use and write log files.

Following is my log4j.properties file which is in my class path:

log4j.appender.R = org.apache.log4j.DailyRollingFileAppender
log4j.appender.R.File = /ParentFolder/ChildFolder/application.log
log4j.appender.R.Append = true
log4j.appender.R.DatePattern = '.'yyy-MM-dd
log4j.appender.R.layout = org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss} %c{1} [%p] %m%n

Following is the code to initialize logging in my main method

final String LOG_FILE = "C:/eclipse_workspace/lib/log4j.properties"; 
      Properties logProp = new Properties();      
      try     
      {      
       logProp.load(new FileInputStream (LOG_FILE));  
            PropertyConfigurator.configure(logProperties);      
            logger.info("Logging enabled");    
      }     
      catch(IOException e)                
      {       
     System.out.println("Logging not enabled");       
                 }

In every java class of the application I have the following code

import org.apache.log4j.*;

private static final Logger logger = Logger.getLogger(TheActualClassName.class);

But I get the following warning messages when I run the app.

log4j:WARN No appenders could be found for logger (com.xxx.myApp.MainProgram.MyFileName).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

What am I doing wrong?? The log file "application.log" is not being generated

Best Answer

May need the following line:

# Set root logger level to INFO and appender to R.
log4j.rootLogger=INFO, R

The root logger is always available and does not have a name.

Since the version 1.2.7, log4j (with the LogManager class) looks for log4j.xml in the classpath first. If the log4j.xml not exists, then log4j (with the LogManager class) looks for log4j.properties in the classpath.

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Spring uses Jakarta Commons Logging as a logging API. In order to log to slf4j, you need to make sure commons-logging is not on the classpath. jcl-over-slf4j is a replacement jar for commons-logging.

If you're using maven, you can detect where commons-logging comes from using mvn dependency:tree and exclude it from all dependencies that require it using dependency exclusions. You might need to run mvn dependency:tree several times though, because it only shows the first occurence of a transitive dependency.

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Java – Proper use cases for Android UserManager.isUserAGoat()

Android R Update:

From Android R, this method always returns false. Google says that this is done "to protect goat privacy":

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this method can
 * now automatically identify goats using advanced goat recognition technology.</p>
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#R}, this method always returns
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public boolean isUserAGoat() {
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    return mContext.getPackageManager()
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}

Previous answer:

From their source, the method used to return false until it was changed in API 21.

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 * @return whether the user making this call is a goat 
 */
public boolean isUserAGoat() {
    return false;
}

It looks like the method has no real use for us as developers. Someone has previously stated that it might be an Easter egg.

In API 21 the implementation was changed to check if there is an installed app with the package com.coffeestainstudios.goatsimulator

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this method can
 * now automatically identify goats using advanced goat recognition technology.</p>
 *
 * @return Returns true if the user making this call is a goat.
 */
public boolean isUserAGoat() {
    return mContext.getPackageManager()
            .isPackageAvailable("com.coffeestainstudios.goatsimulator");
}

Here is the source and the change.