Use log4j in Android

When i am developing an application for Android, i am already looking for a good library or functionality for logging mechanism. For Java applications i am already using log4j and log4net for .net applications. When i am researching a log4j capabilities on Android, i found a good library which is called android-logging-log4j. It is an open source and it has a simple and good LogConfigurator class.

When i was playing with this library, i have created a simple application. I hope it will be helpful for you.

First, add log4j-#.#.#.jar and android-logging-log4j-#.#.#.jar files to project add a reference.

After that, i have created a helper class for configuration and logger object.

public class Log4jHelper {

    private final static LogConfigurator _logConfigurator = new LogConfigurator();

    public static void Configure(String fileName, String filePattern,
        int maxBackupSize, long maxFileSize) {

        // set the name of the log file
        _logConfigurator.setFileName(fileName);
        // set output format of the log line
        _logConfigurator.setFilePattern(filePattern);
        // Maximum number of backed up log files
        _logConfigurator.setMaxBackupSize(maxBackupSize);
        // Maximum size of log file until rolling
        _logConfigurator.setMaxFileSize(maxFileSize);

        // configure
        _logConfigurator.configure();

    }

    public static Logger getLogger(String name) {
        Logger logger = Logger.getLogger(name);
        return logger;
    }

}

And, i have written a few line of codes in Application onCreate event for log4j configuration

public class Log4jApplication extends Application {

    @Override
    public void onCreate() {
        super.onCreate();

        // configure log4j
        configureLog4j();
    }

    private void configureLog4j() {

        String fileName = Environment.getExternalStorageDirectory() + "/" + "log4j.log";
        String filePattern = "%d - [%c] - %p : %m%n";
        int maxBackupSize = 10;
        long maxFileSize = 1024 * 1024;

        Log4jHelper.Configure(fileName, filePattern, maxBackupSize, maxFileSize);
    }

}

Of course don't forget the WRITE_EXTERNAL_STORAGE permission in AndroidManifest.xml file

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

We are ready :) Let's write some logs :

Logger mLog = Logger.getLogger(Log4jActivity.class);

// write some logs
mLog.error("This is an error");
mLog.info("This is an info");
mLog.warn("This is a warn");

// write some exception
try {
    String dummyString = null;
    if (dummyString.equals("something")) {
        int dummyInt = 1;
    }
} catch (Exception ex) {
    mLog.error(ex.toString(), ex);
}

You can find source code and sample usage on