JavaFx TableView - saving edits on focus lost doesn't work if focus is given to same column

Question

I have been pulling my hair out over this issue and cannot seem to find any logic fix.

I am attempting to save the contents of a table cell when the user clicks away. After following this tutorial I have table cells that save their edits when focus is lost except when the user clicks into the same column.

I know why the issue is happening, the commitEdit() method will return immediately if isEditing() is true (which it is when you click into the same column.

 public void commitEdit(T newValue) {
        if (! isEditing()) return;
    ...

I tried overriding the method to no avail. I can force update the cell contents but I don't know how to force edit the cell value without knowing what cell I am in.

If there is a way for me to get the field name of the cell I am in, I could use Reflection to force an update but I don't know how to get the field name or if it's even possible.

Answer 1

It seems all you are looking for is a way for the cell to process new (or old) values and write them back to the model. Why not just provide a callback in the form of a BiConsumer<S,T>?

public class EditingCell<S,T> extends TableCell<S,T> {

    private final BiConsumer<S,T> updater ;

    public EditingCell(BiConsumer<S,T> updater) {
        this.updater = updater ;
    }

    // ....

    // not really sure what this method is for:
    public void commit(T val) {
        S rowValue = getTableView().getItems().get(getIndex());
        updater.accept(rowValue, val);
    }

    // wouldn't this be better?
    @Override
    public void commitEdit(T newValue) {
        super.commitEdit(newValue);
        S rowValue = getTableView().getItems().get(getIndex());
        updater.accept(rowValue, val);
    }

    // ...
}

Then you would do things like:

TableView<Person> table = new TableView<>();

TableColumn<Person, String> firstNameColumn = new TableColumn<>("First Name");
firstNameColumn.setCellValueFactory(cellData -> cellData.getValue().firstNameProperty());
firstNameColumn.setCellFactory(col -> new EditingCell(Person::setFirstName));

Answer 2

After digging, I found out how to get the property name of a column. With that I went ahead and wrote some generic reflections to force update. I wrapped everything in a method commit(Object val) for ease of use. These are modifications to EditCell class used here.

Disclaimer: This only works if you use a PropertyValueFactory and follow naming conventions in your row classes. This is also very fickle code, use and modify at your own discretion.

I modified the cell to be a generic cell with public static class EditingCell<S, T> extends TableCell<S, T>. Everything else from the tutorial should still be the same, if not feel free to let me know and I'll update here accordingly.

public void commit(Object val) {

        // Get the table
        TableView<S> t = this.getTableView();

        // Get the selected row/column
        S selectedRow = t.getItems().get(this.getTableRow().getIndex());
        TableColumn<S, ?> selectedColumn = t.getColumns().get(t.getColumns().indexOf(this.getTableColumn()));

        // Get current property name
        String propertyName = ((PropertyValueFactory) selectedColumn.getCellValueFactory()).getProperty();

        // Create a method name conforming to java standards ( setProperty )
        propertyName = ("" + propertyName.charAt(0)).toUpperCase() + propertyName.substring(1);

        // Try to run the update
        try {

            // Type specific checks - could be done inside each setProperty() method
            if(val instanceof Double) {
                Method method = selectedRow.getClass().getMethod("set" + propertyName, double.class);
                method.invoke(selectedRow, (double) val);
            }
            if(val instanceof String) {
                Method method = selectedRow.getClass().getMethod("set" + propertyName, String.class);
                method.invoke(selectedRow, (String) val);
            }
            if(val instanceof Integer) {
                Method method = selectedRow.getClass().getMethod("set" + propertyName, int.class);
                method.invoke(selectedRow, (int) val);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        // CommitEdit for good luck
        commitEdit((T) val);
    }

and then since the text field won't update, I forced an update on it in cancelEdit(). This is slightly specific to my case ( I want a default of 0.0 and only accepted values are doubles ) - modify it as needed.

@Override
public void cancelEdit() {
    super.cancelEdit();

    // Default value
    String val = "0.0";

    // Check to see if there's a value
    if (!textField.getText().equals(""))
        val = textField.getText();

    // Set table cell text
    setText("" + val);
    setGraphic(null);
}