Creating log4j log file for each run with Date and timestamp

EDIT - removed the DailyFileAppender suggestion.

You can create your own FileAppender, like this:

public class NewFileOnRebootAppender extends FileAppender {

    public NewFileOnRebootAppender() {
    }

    @Override
    public void setFile(String file) {
        super.setFile(prependDate(file));
    }

    private static String prependDate(String filename) {
        return System.currentTimeMillis() + "_" + filename;
    }
}

And use it like this:

log4j.appender.fileOnReboot=yourPackage.NewFileOnRebootAppender
log4j.appender.fileOnReboot.File=appLogOnReboot.log
log4j.appender.fileOnReboot.layout=org.apache.log4j.PatternLayout
log4j.appender.fileOnReboot.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

The naming of the file is not perfect, but you get the idea..