JavaFX: Adding rows to TableView with a HashMap binding

Question

Suppose that I have a map collection:

ObserableHashMap<K,V> map = FXCollections.observableHashMap();

I put 1 record into this map during fxml controller initialization, then wrap it as ObservableList:

ObservableList<ObserableHashMap.Entry<K,V>> list = FXCollections.observableArrayList(map.entrySet());

then setitems for my tableView.setItems(list);

Everything is fine when I run this JavaFX app and 1 record is showing.

Question is that:

When I add more records later to my map, my TableView will not refresh these records.

How could I bind a dynamical map collection into my TableView?

Thanks

Answer 1

If you use an ObservableList of ObservableMaps as your TableView's data structure

ObservableList<ObservableMap> rowMaps = FXCollections.observableArrayList();
tableView.setItems(rowMaps);

and implement your own ObservableMapValueFactory

import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.value.ObservableValue;
import javafx.collections.MapChangeListener;
import javafx.collections.ObservableMap;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableColumn.CellDataFeatures;
import javafx.util.Callback;

public class ObservableMapValueFactory<V> implements
        Callback<TableColumn.CellDataFeatures<ObservableMap, V>, ObservableValue<V>> {

    private final Object key;

    public ObservableMapValueFactory(Object key) {
        this.key = key;
    }

    @Override
    public ObservableValue<V> call(CellDataFeatures<ObservableMap, V> features) {
        final ObservableMap map = features.getValue();
        final ObjectProperty<V> property = new SimpleObjectProperty<V>((V) map.get(key));
        map.addListener(new MapChangeListener<Object, V>() {
            public void onChanged(Change<?, ? extends V> change) {
                if (key.equals(change.getKey())) {
                    property.set((V) map.get(key));
                }
            }
        });
        return property;
    }
}

and then set it as the cell value factory for your column(s)

column.setCellValueFactory(new ObservableMapValueFactory<String>(columnId));

all changes to your data are reflected in the TableView, even changes only affecting the ObservableMaps.

Answer 2

The answer from ItachiUchiha use the columns as keys and the rows as individual maps. If you'd like one map with the rows as keys->values, you'll have to add a listener to the map that will change the list when you add or delete. I did something similar here. https://stackoverflow.com/a/21339428/2855515

Answer 3

You can bind a map directly to a TableView, consider this example from the JavaFX documentation :

import java.util.HashMap;
import java.util.Map;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.MapValueFactory;
import javafx.scene.control.cell.TextFieldTableCell;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;
import javafx.util.Callback;
import javafx.util.StringConverter;

public class TableViewSample extends Application {

    public static final String Column1MapKey = "A";
    public static final String Column2MapKey = "B";

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) {
        Scene scene = new Scene(new Group());
        stage.setTitle("Table View Sample");
        stage.setWidth(300);
        stage.setHeight(500);

        final Label label = new Label("Student IDs");
        label.setFont(new Font("Arial", 20));

        TableColumn<Map, String> firstDataColumn = new TableColumn<>("Class A");
        TableColumn<Map, String> secondDataColumn = new TableColumn<>("Class B");

        firstDataColumn.setCellValueFactory(new MapValueFactory(Column1MapKey));
        firstDataColumn.setMinWidth(130);
        secondDataColumn.setCellValueFactory(new MapValueFactory(Column2MapKey));
        secondDataColumn.setMinWidth(130);

        TableView table_view = new TableView<>(generateDataInMap());

        table_view.setEditable(true);
        table_view.getSelectionModel().setCellSelectionEnabled(true);
        table_view.getColumns().setAll(firstDataColumn, secondDataColumn);
        Callback<TableColumn<Map, String>, TableCell<Map, String>>
            cellFactoryForMap = new Callback<TableColumn<Map, String>,
                TableCell<Map, String>>() {
                    @Override
                    public TableCell call(TableColumn p) {
                        return new TextFieldTableCell(new StringConverter() {
                            @Override
                            public String toString(Object t) {
                                return t.toString();
                            }
                            @Override
                            public Object fromString(String string) {
                                return string;
                            }                                    
                        });
                    }
        };
        firstDataColumn.setCellFactory(cellFactoryForMap);
        secondDataColumn.setCellFactory(cellFactoryForMap);

        final VBox vbox = new VBox();

        vbox.setSpacing(5);
        vbox.setPadding(new Insets(10, 0, 0, 10));
        vbox.getChildren().addAll(label, table_view);

        ((Group) scene.getRoot()).getChildren().addAll(vbox);

        stage.setScene(scene);

        stage.show();
    }

    private ObservableList<Map> generateDataInMap() {
        int max = 10;
        ObservableList<Map> allData = FXCollections.observableArrayList();
        for (int i = 1; i < max; i++) {
            Map<String, String> dataRow = new HashMap<>();

            String value1 = "A" + i;
            String value2 = "B" + i;

            dataRow.put(Column1MapKey, value1);
            dataRow.put(Column2MapKey, value2);

            allData.add(dataRow);
        }
        return allData;
    }
}

More information can be found here