public Set keySet(){
  if (keySet == null)   keySet=new SynchronizedSet(new KeySet(),this);
  return keySet;
}

public Set keySet ( ) { if ( keySet == null ) keySet = new SynchronizedSet ( new KeySet ( ) , this ) ; return keySet ; }
returns a set view of the keys contained in this cache . the set is backed by the cache , so changes to the cache are reflected in the set , and vice - versa . the set supports element removal ( which removes the corresponding entry from the cache ) , but not element addition .
