JavaFX: Adding rows to TableView with a HashMap binding - hashmap

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

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

Answer 3

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