code: public void setPoolClass(Class poolClass)
          throws IllegalStateException
      {
          synchronized(this)
          {
              if (_class!=poolClass)
              {
                  if (_running>0)
                      throw new IllegalStateException("Thread Pool Running");
                  if (!PondLife.class.isAssignableFrom(poolClass))
                      throw new IllegalArgumentException("Not PondLife: "+poolClass);
                  _class=poolClass;
                  _className=_class.getName();
              }
          }
      }
docs: Set the class.
  @param poolClass The class
  @exception IllegalStateException If the pool has already
  been started.