JavaFX: How to overwrite button action in custom Dialog

I work on desktop application based on JDK 8 and JavaFX.

I created custom dialog class with 2 buttons(finish and cancel). My goal is to return the list of strings added in dialog (after clicking finish button, dialog returns list. Cancel makes return empty list).

I have problem, beacause function showAndWait return type of button which I clicked (‘ButtonType.FINISH’ or ‘ButtonType.CANCEL’). My goal is to override default action on finish and close button and I want to return list instead of return button type.

It’s always possible to create custom buttons, however, it would be better to use those already provided by JavaFX.

In response, you can use any of the JVM languages (Java/Kotlin/Scala).

Code:

class MyDialog : Dialog<MutableList<String>>() {
  val listToReturn: MutableList<String> = mutableListOf()
    
  init {
    val dialogPane: DialogPane = this.dialogPane

    dialogPane.buttonTypes.addAll(ButtonType.FINISH, ButtonType.CANCEL)
  }
}

val myDialog: MyDialog = MyDialog()

// here I got ButtonType ('ButtonType.FINISH' or 'ButtonType.CANCEL'), not list of string
myDialog.showAndWait().ifPresent { list -> println(list) }

Answer

You need to use a result converter

public class MyDialog extends Dialog<List<String>> {
    ArrayList<String> returnList = new ArrayList<>();
    public MyDialog() {
        returnList.add("test 1");
        returnList.add("test 2");
        this.getDialogPane().getButtonTypes().addAll(ButtonType.FINISH, ButtonType.CANCEL);

        setResultConverter(dialogButton -> {
           if (dialogButton == ButtonType.FINISH) {
               return returnList;
           }
           return new ArrayList<>();
        });
    }
}

and for the application side

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

    @Override
    public void start(Stage primaryStage) {
        MyDialog myDialog = new MyDialog();
        myDialog.showAndWait().ifPresent(System.out::println);
    }
}