java set转list

 private final ZKWatchManager watchManager;

    List<String> getDataWatches() {
        synchronized(watchManager.dataWatches) {
            List<String> rc = new ArrayList<String>(watchManager.dataWatches.keySet());
            return rc;
        }
    }
    List<String> getExistWatches() {
        synchronized(watchManager.existWatches) {
            List<String> rc =  new ArrayList<String>(watchManager.existWatches.keySet());
            return rc;
        }
    }
    List<String> getChildWatches() {
        synchronized(watchManager.childWatches) {
            List<String> rc = new ArrayList<String>(watchManager.childWatches.keySet());
            return rc;
        }
    }