private void clean(){
  SREntry entry=(SREntry)fReferenceQueue.poll();
  while (entry != null) {
    removeEntry(entry);
    entry=(SREntry)fReferenceQueue.poll();
  }
}

private void clean ( ) { SREntry entry = ( SREntry ) fReferenceQueue . poll ( ) ; while ( entry != null ) { removeEntry ( entry ) ; entry = ( SREntry ) fReferenceQueue . poll ( ) ; } }
removes stale symbols from the table .
