Re: Updates to a single class instance

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 18 Aug 2007 16:16:53 -0400

Message-ID:

<D4OdnWMc-74rzlrbnZ2dnUVZ_sKqnZ2d@comcast.com>

unlikeablePorpoise@gmail.com wrote:

Thanks for your replies.

Simply to avoid top-posting will indicate thanks.

package org.collector;

Are you an org, named "collector"?

The org domain implies non-profit organizations.

public class Collector{

    private Collector() {}

    private static Collector ref;

    public static synchronized Collector getCollectorObject()

Since everything in Java is an object, having "Object" in your method name is
redundant.

{
if(ref == null)

This is overuse of lazy initialization.

Just establish the object in the class initializer.

         {
            System.out.println("ref is null");
            ref = new Collector();
        }
        else
        {
            System.out.println("ref exists");
        }

        return ref;
    }
}

When I call 'Collector col = Collector.getCollectorObject();' twice in
two different classes, it returns "ref is null". However, if I do this
twice in the same class method, ie

I don't know exactly why this happens, but I bet you'll get rid of the problem
altogether like this

public class Collector
{
   private Collector()
   {
   }
   private static final Collector UNIQUE = new Collector();
   // this has the advantage of making the variable non-replaceable
   // and eliminating the need for synchronization

   public static Collector getCollector()
   {
     return UNIQUE;
   }
}

--
Lew