可能为null时的Java setCellValueFactory lambda表达式

Question

I have the following line of code to set up a column in JavaFX:

branchActionColumn.setCellValueFactory(cd -> cd.getValue().getAction().getTextProperty());

This typically works fine. However, sometimes getAction() returns null (and that can be normal behavior). In that case I'd like to just display the empty string "". How could I do that?

I've tried:

branchActionColumn.setCellValueFactory(cd -> (cd.getValue().getAction() == null) ? new SimpleStringProperty("") : cd.getValue().getAction().getTextProperty());

While this displays the initial value of the property in the TableView, any subsequent changes made to the property are not reflected in the TableView. I believe this is because I am creating a new property inside the lambda expression.

If I go back to the line branchActionColumn.setCellValueFactory(cd -> cd.getValue().getAction().getTextProperty()); then the TableView responds appropriately whenever the property changes. This is the behavior that I want. I just also want it to handle the case when getAction() returns null.

Here is a similar question, but it's for C# and it's not related to a CellValueFactory: C#, in List<>.ConvertAll method using lambda expression, how to make a filter when the object is null?

Answer 1

Try to use optional

branchActionColumn.setCellValueFactory(cd -> 
    Optional.ofNullable(cd.getValue().getAction())
        .map(action -> action.getTextProperty())
        .orElseGet(() -> new SimpleStringProperty(""))
);