Add log4j capability to append two event message on a single line in the console output. Example: log.info("hello \n"); log.info("world !"); Results: [INFO] hello world !

InteractiveRollingFileAppender.java

import org.apache.log4j.RollingFileAppender
import org.apache.log4j.helpers.CountingQuietWriter
import org.apache.log4j.spi.LoggingEvent

/**
 * Interactive file appender
 *
 * Provide a capability to append two event message on a single line in a log file.
 *
 * Example:
 * log.info("hello \n");
 * log.info("world !");
 *
 * Results:
 * [INFO] hello world !
 *
 * @author vicben01
 */
class InteractiveRollingFileAppender extends RollingFileAppender
{
  public boolean immediateFlush = false

  @Override
  protected void subAppend(LoggingEvent event)
  {
    SingleLineAppenderStrategy.subAppend(event, this)

    if (fileName != null && qw != null)
    {
      long size = ((CountingQuietWriter) qw).getCount();
      if (size >= maxFileSize && size >= nextRollover)
      {
        rollOver();
      }
    }
  }
}

SingleLineAppenderStrategy.java

package com.arm.pipd.scf.utils.log4j

import org.apache.log4j.AppenderSkeleton
import org.apache.log4j.Layout
import org.apache.log4j.WriterAppender
import org.apache.log4j.spi.LoggingEvent

/**
 * SingeLineAppender strategy.
 *
 * Enables to append two event message on a single line in a log file.
 *
 * @author vicben01
 */
class SingleLineAppenderStrategy
{
  static void subAppend(LoggingEvent event, WriterAppender writerAppender)
  {
    // Write message
    writerAppender.qw.write(text(event, writerAppender));

    if (writerAppender.layout.ignoresThrowable())
    {
      String[] s = event.getThrowableStrRep();
      if (s != null)
      {
        int len = s.length;
        for (int i = 0; i < len; i++)
        {
          writerAppender.qw.write(s[i]);
          writerAppender.qw.write(Layout.LINE_SEP);
        }
      }
    }

    if (writerAppender.shouldFlush(event))
    {
      writerAppender.qw.flush();
    }
  }

  static String text(LoggingEvent event, AppenderSkeleton appenderSkeleton)
  {
    if(!(event.message instanceof String))
      return "";

    // Dirty text formatting
    String text
    if(event?.message
        && (((String) event.message).startsWith('done')
        || ((String) event.message).startsWith('fail')
        || ((String) event.message).startsWith('using')))
    {
      text = event.message + '\n'
    }
    else
      text = appenderSkeleton.layout.format(event)

    // Remove line separator if line is not finished
    if(!endOfLine(event))
      text = text.substring(0, text.length() - 4)
    return text
  }

  /**
   * Detect if event.message end with /n
   * and remove /n if placed at the end
   *
   * @param event send by logger
   * @return true if message does not end with \n
   */
  static boolean endOfLine(LoggingEvent event)
  {
   String msg = (String) event.message
   if (msg.endsWith('/n'))
     return false
   return true
  }

}