Re: what is wrong with File.createNewFile()

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 01 Dec 2007 17:42:25 -0500

Message-ID:

<XcCdnecUStzMfszanZ2dnUVZ_hqdnZ2d@comcast.com>

Drazen Gemic wrote:

You don't need to obtain the system class loader, just 'install' the
class files for this object in TomCat's classpath. Class loaders
delegate to their parent and should only load objects which are not
known to the parent class loader. This does mean that this class will be
outside the application(s) and you will need access to the TomCat
configuration.

I've found a simple solution here:

http://enricogi.blogspot.com/2007/04/singleton-for-tomcat.html

I checked, and it seems to be the same object for all apps. A method
'showTime()'
returns the same value of hash key and creation time. I think that's
it. Many thanks to
everybody who helped me.

package lambdacommon;
//
import java.util.*;
//
public class Mutex {
//

// You could go a step further and make 'createdAt' final.
// and instance members generally should be private, although
// package-private isn't so bad

private final

long createdAt

= new Date().getTime();

boolean isLocked;

private

static Mutex instance=new Mutex();
//
public static Mutex getInstance()
   {
   return instance;
   }
//
private Mutex()
   {
   }
//
public synchronized void lock()
   {
   try {

// shouldn't this be while instead of if?

      if(isLocked) wait();
      }
   catch(InterruptedException ipx) {}
   isLocked=true;
   }
//
public synchronized void unlock()
   {
   if(isLocked)
      {
      isLocked=false;
      notify();
      }
   }
//
public String showTime()
   {
   return toString() + " created at "+createdAt;
   }
}

--
Lew