JavaFX Spinner disable buttons on empty editor - javafx

Question

Ok, heres my situation. I need to disable both spinner buttons when the Editor is empty, which is the final piece i need to complete this "custom" component. Heres my SSCCE.
When the focus is lost: Default value sets to zero and text is updated.
It only accepts decimal values with 2 decimal places, it is meant to only accept money or percentages values.
Nothing else to add.
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Spinner;
import javafx.scene.control.SpinnerValueFactory;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class test extends Application{
#Override
public void start(Stage primaryStage) throws Exception {
VBox v = new VBox();
v.setPadding(new Insets(20));
Spinner<Double> spinner = new Spinner<>();
spinner.setEditable(true);
Button dummy = new Button("dummy focus");
v.getChildren().addAll(spinner,dummy);
//----------------------------------HERE IS EVERYTHING RELATED TO THE SPINNER---------------------------------------------
spinner.setValueFactory(new SpinnerValueFactory.DoubleSpinnerValueFactory(0, 100));
spinner.getValueFactory().setValue(0.0);
spinner.getEditor().textProperty().addListener((obs,old,gnu)->{
if(gnu.isEmpty()) {
System.out.println("empty, buttons should be disabled here, they will be disabled after this ");
spinner.getValueFactory().setValue(0.0);
return;
}
System.out.println("enabling buttons");
if(!gnu.matches("^\\d*\\.?\\d*$")) {
try {
spinner.getEditor().setText(old);
spinner.getValueFactory().setValue(Double.parseDouble(old));
}catch (NumberFormatException e) {
System.out.println("invalid string, previous value was empty, no biggie you are safe: Current value : "+spinner.getValueFactory().getValue());
}
} else {
if((Double.parseDouble(gnu)*100)%1!=0) {
spinner.getEditor().setText(old);
spinner.getValueFactory().setValue(Double.parseDouble(old));
}
/*
* You can use this to validate inside a range, for example. PERCENTAGES : 0 ~ 100
*
double val = Double.parseDouble(gnu)*100;
if(val%1!=0 || val>10000 || val<0) {
spinner.getEditor().setText(old);
spinner.getValueFactory().setValue(Double.parseDouble(old));
}
*/
}
});
spinner.getEditor().setOnKeyPressed(e->{
switch (e.getCode()) {
case UP:
spinner.increment(1);
break;
case DOWN:
spinner.decrement(1);
break;
default:
break;
}
});
spinner.setOnScroll(e->{
if(e.getDeltaY()>0)
spinner.increment(1);
else
spinner.decrement(1);
});
spinner.getEditor().focusedProperty().addListener((obs,old,niu)->{
if(!niu && spinner.getEditor().getText().isEmpty()) {
spinner.getEditor().setText("0");
spinner.getValueFactory().setValue(0.0);
}
});
//-----------------------------------------------------------------------------------------------------------------------------------------
Scene sc = new Scene(v);
primaryStage.setScene(sc);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
EDIT:
It also happens with keypress and scroll events.

Answer 1

I was also searching for a way to disable only the buttons. I needed to disable changing the Spinner's value while still allowing copy/paste, so I did some digging in the source code.
What I found was that, while the buttons are not actually part of the Spinner object itself, they're part of the Spinner's SpinnerSkin (they're also not Buttons, but StackPanes), so I managed to disable only the buttons with the following (in Kotlin):
val editing = SimpleBooleanProperty(false)
val spinner = Spinner<Int>()
spinner.skinProperty().addListener { observable, oldValue, newValue ->
// only bind if the skin is an instance of `SpinnerSkin`
if (newValue != null && newValue is SpinnerSkin<*>) {
(skin as SpinnerSkin<*>).children
// only select the children that are `StackPane`s (the buttons)
.filter { it is StackPane }
// bind the `disableProperty` of the buttons to our property for whether we're editing
.forEach { disableProperty().bind(editing.not()) }
}
}
I had to listen to the property change because the the skinProperty is not set on initialization, but only after the CSS gets processed. If you are absolutely sure that your spinner has already displayed and the skin is set, you can just call getSkin instead.

Answer 2

I'm afraid you can't disable only the spinner's buttons. But what about setting the value just after the Editor (which is actually the TextField) is empty? By using such a solution you don't get any exceptions after clicking buttons - value is just incremented from 0. I modified your gnu.isEmpty() code a little.
if(gnu.isEmpty()) {
System.out.println("empty, buttons should be disabled here, they will be disabled after this ");
double valueToSet = 0.0;
spinner.getValueFactory().setValue(valueToSet);
Platform.runLater(() -> spinner.getEditor().setText(Double.toString(valueToSet)));
return;
}
Another thing is, that your code allows to put '0' as a first number, even if there are another numbers after. Check that code, should fix the problem (swap it with the whole if/else statement starting with if(!gnu.matches("^\\d*\\.?\\d*$"))):
if (!isDouble(gnu)) {
gnu = old;
}
spinner.getEditor().setText(gnu);
Where isDouble is a method:
private boolean isDouble(String string) {
boolean startsWithZero =
string.startsWith("0") &&
(string.length() > 1) &&
(!string.startsWith("0."));
boolean minusZeroCondition =
string.startsWith("-0") &&
(string.length() > 2) &&
(!string.startsWith("-0."));
boolean containsTypeSpecificLetters =
Pattern.matches(".*[a-zA-Z].*", string);
boolean isEmpty = string.equals("");
boolean isMinus = string.equals("-");
try {
Double.parseDouble(string);
return !(startsWithZero || minusZeroCondition || containsTypeSpecificLetters);
} catch (IllegalArgumentException exception) {
return isEmpty || isMinus;
}
}