Java tutorial
import java.util.HashMap; import java.util.Map; import javafx.collections.FXCollections; import javafx.collections.MapChangeListener; import javafx.collections.ObservableMap; public class Main { public static void main(String[] args) { Map<String, String> map = new HashMap<String, String>(); ObservableMap<String, String> observableMap = FXCollections.observableMap(map); observableMap.addListener(new MapChangeListener() { @Override public void onChanged(MapChangeListener.Change change) { System.out.println("change! "); } }); observableMap.put("key 1", "value 1"); map.put("key 2", "value 2"); } }