JavaFx - How to get button array index if value is all the same

Question

I have an issue when I tried to create multiple buttons with the same value of "x". How can I fix this issue or perhaps get the value of the buttons and then delete the specific element in an array with the same index as my button without deleting other elements as it loops through the for loop?

Button[] delButton = new Button[sizeOfIt]; //sizeOfIt is the size of array

for (int m=0; m <sizeOfIt; m++) {
    delButton[m]  = new Button("x");
}


for(int x = 0; x < delButton.length; x++) {                          
    delButton[x].setOnAction(new EventHandler<ActionEvent>() {     

        public void handle(ActionEvent event) {
        //  delete the element in the array with the same index as my button i clicked
        }
    });
}

Are you trying to remove the Button from the Scene or remove it from the Array? — SedJ601
– SedJ601, Commented Nov 8, 2018 at 19:41

azro · Accepted Answer · 2018-11-08 18:51:35Z

1

You could handle this using the position of the button, it'll leave an empty box where the button was :

for(int x = 0; x < delButton.length; x++) {     
    final index = x;                     
    delButton[x].setOnAction(new EventHandler<ActionEvent>() {     
        public void handle(ActionEvent event) {
            delButton[index] = null;
        }
    });
}

answered Nov 8, 2018 at 18:51

azro

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1 Comment

SedJ601 Over a year ago

I am curious if this throws a NullPointerExecption? One would assume that if these buttons are in a Scene and set to null without removing them from the Scene, a NullPointerExecption should be thrown.

SedJ601 · Accepted Answer · 2018-11-08 19:59:44Z

@azro example keeps up with the index to get a reference to the Buttons. This example uses actionEvent.getSource() to get a reference to the Buttons.

import java.util.Arrays;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Control;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Main extends Application
{
    int sizeOfIt = 10;

    @Override
    public void start(Stage primaryStage)
    {
        Button[] delButton = new Button[sizeOfIt]; //sizeOfIt is the size of array
        VBox vBox = new VBox();

        for (int m = 0; m < sizeOfIt; m++) {
            delButton[m] = new Button(m + "x");
            delButton[m].setOnAction(actionEvent -> {
                for (int i = 0; i < delButton.length; i++) {
                    if (delButton[i] != null && delButton[i].equals((Button) actionEvent.getSource())) {
                        vBox.getChildren().remove(delButton[i]);
                        delButton[i] = null;
                        System.out.println(Arrays.toString(delButton));
                    }
                }
            });
        }

        vBox.getChildren().addAll(delButton);
        vBox.setMaxSize(Control.USE_PREF_SIZE, Control.USE_PREF_SIZE);

        StackPane root = new StackPane(vBox);
        Scene scene = new Scene(root);
        primaryStage.setScene(scene);
        primaryStage.show();

    }

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

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