Check which Button object is clicked using JavaFX

Question

I am making a basic calculator but I am unsure of how to check if a certain Button has been clicked. I want to use an array of Button objects and then check to see if the button clicked matches a button object in the array. My code for this is below.

Button[] digitButtons = { bt0, bt1, bt2, bt3, bt4, bt5, bt6, bt7, bt8, bt9 };

for (int index = 0; index < 9; index++) {
    int position = -1;
    if (buttonClicked == digitButtons[index]) {
        position = index;
        break;
    }
}

Solution 1

Here is an example:

public class Main extends Application {
    private int lastClickedIndex = -1; 

    @Override
    public void start(Stage primaryStage) {
        try {
            BorderPane root = new BorderPane();
            Scene scene = new Scene(root, 400, 400);


            Button[] digitButtons = new Button[10];
            for(int i = 0; i < 10; i++) {
                final int buttonInd = i;
                digitButtons[i] = new Button(Integer.toString(i));
                digitButtons[i].setOnAction(e -> {
                    System.out.println("Button pressed " + ((Button) e.getSource()).getText());
                    lastClickedIndex = buttonInd;
                });
            }

            root.setCenter(new HBox(digitButtons));

            primaryStage.setScene(scene);
            primaryStage.show();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

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

Note: It is unnecessary to get the index as the Button is exactly specified as the event source: e.getSource().

Solution 2

a simple way like

---

FXML

create 2 buttons call B1 and B2, and add fx:id for each button)

<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" prefHeight="200" prefWidth="320" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8" fx:controller="ask.FXMLDocumentController">
    <children>
        <Button fx:id="B1" layoutX="94.0" layoutY="106.0" text="B1" />
        <Button fx:id="B2" layoutX="195.0" layoutY="106.0" text="B2" />
    </children>
</AnchorPane>

Controller

use setOnAction method to change value

Button name must same as what fx:id set

import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;

public class FXMLDocumentController implements Initializable {

    @FXML Button B1;
    @FXML Button B2;
    int whichIsLastClicked = -1;

    public void initialize(URL url, ResourceBundle rb) 
    {
        B1.setOnAction(e->whichIsLastClicked=1);
        B2.setOnAction(e->whichIsLastClicked=2);
    }    

}