Re: How to implement this?

Chris wrote:

The latter likely avoids the threading complications of the unsynchronized
test-and-set idiom you presented. In a case like this there is no advantage
to lazy initialization.

If your Logger class is from log4j it is already thread safe, of course.

One more approach is a static initializer:

public class Tester
{
    private static final BufferedWriter logger;
    static
    {
      String path = "/home/xi/Desktop/D2V/validation/";
      try
      {
       logger = new BufferedWriter( new FileWriter(
                    new File( path, "log" )));
      }
      catch ( IOException exc )
      {
       String msg = "Cannot open log file \""+ path +"log\"";
       throw new IllegalStateException( msg, exc );
      }
    }
...

}

This is like using the static init() method without naming the method. The
body of the static initializer could be the body of a static initialization
method like initLogger().