AsyncMapLoader.java

AsyncMapLoader.java

interface Loader<T> {
  void add(T element);
  boolean isFinished();
}

interface MapLoader<K, V> {
  void loadAllKeys(Loader<K> loader);
}

class MyMapLoader<String, String> {
  void loadAllKeys(Loader<String> loader) {
    final Connection conn = connect();
    final ResultSet rs = query(conn);

    while( rs.next() && !loader.isFinished() )
      loader.add( rs.getString("Id") );
    
    rs.close();
    conn.close();            
  }
}