Singletond - a variant

Question

I would appreciate comments for the following variant of the singleton pattern:
// Foo.java
package bar;
public interface Foo
  public static final Foo fooImpl = new FooImpl();
  public void process();
// FooImpl.java
package bar;
public class FooImpl implements Foo
  protected FooImpl(){}
  public void process()
    //some implementation
}So any client can now call process() like:
   Foo.fooImpl.process();    Here are the features of the above approach:
1. only one instance of FooImpl exists
2. clients of FooImpl are tied only to the interface Foo
Where I am assuming that all clients of FooImpl are outside
the package where FooImpl belongs.
The above technique would be useful when Struts
action classes need to invoke methods on the service facade
in the business layer.
Thanks,
Nalla

Answer 1

also it allows for the following singleton breaking
code:
package any;
public class FooTwo extends FooImpl
Foo[] foos = new Foo[10];
for (int i = 0; i < foos.length; i++)
foos[i] = new FooTwo();
I understand this scenario. In this case we would have Foo as
// Foo.java
package bar;
import any.FooTwo;
public interface Foo{ 
  public static final Foo fooImpl = new FooTwo(); 
  public void process();
}I am assuming that only one usable implementation of Foo exists.