How to get GridPane Row and Column IDs on Mouse Entered in each cell of Grid in JavaFX?

Solution 1:

You can get the values by calling GridPane.getColumnIndex(node) and GridPane.getRowIndex(node).

You haven't shown what you're putting in the grid pane, and even whether you are populating it in FXML or in Java, but here's some basic functionality. Here I (tediously) populate the GridPane in FXML, it might be better to populate it in Java (i.e. in the controller), depending on your use case. (That way, the handler gets a bit cleaner too.)

Controller class:

import javafx.fxml.FXML;
import javafx.scene.Node;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.GridPane;


public class GridPaneTrackingController {

    @FXML
    private void mouseEntered(MouseEvent e) {
        Node source = (Node)e.getSource() ;
        Integer colIndex = GridPane.getColumnIndex(source);
        Integer rowIndex = GridPane.getRowIndex(source);
        System.out.printf("Mouse entered cell [%d, %d]%n", colIndex.intValue(), rowIndex.intValue());
    }
}

If you don't want to define the contents of the cells in FXML, then you can just define them in the controller. That makes things cleaner, as you can just register the listener when you define them:

import javafx.fxml.FXML;
import javafx.scene.layout.ColumnConstraints;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Pane;
import javafx.scene.layout.Priority;
import javafx.scene.layout.RowConstraints;


public class GridPaneTrackingController {

    @FXML
    private GridPane grid ;

    public void initialize() {
        int numCols = 4 ;
        int numRows = 4 ;

        for (int i = 0 ; i < numCols ; i++) {
            ColumnConstraints colConstraints = new ColumnConstraints();
            colConstraints.setHgrow(Priority.SOMETIMES);
            grid.getColumnConstraints().add(colConstraints);
        }

        for (int i = 0 ; i < numRows ; i++) {
            RowConstraints rowConstraints = new RowConstraints();
            rowConstraints.setVgrow(Priority.SOMETIMES);
            grid.getRowConstraints().add(rowConstraints);
        }

        for (int i = 0 ; i < numCols ; i++) {
            for (int j = 0; j < numRows; j++) {
                addPane(i, j);
            }
        }
    }

    private void addPane(int colIndex, int rowIndex) {
        Pane pane = new Pane();
        pane.setOnMouseEntered(e -> {
            System.out.printf("Mouse enetered cell [%d, %d]%n", colIndex, rowIndex);
        });
        grid.add(pane, colIndex, rowIndex);
    }

}

FXML:

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.layout.GridPane?>

<GridPane xmlns:fx="http://javafx.com/fxml/1" 
    fx:controller="GridPaneTrackingController" 
    fx:id="grid" gridLinesVisible="true">

</GridPane>

Application:

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

public class GridPaneTrackingExample extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        GridPane root = FXMLLoader.load(getClass().getResource("GridPaneTrackingExample.fxml"));
        primaryStage.setScene(new Scene(root, 800, 800));
        primaryStage.show();
    }

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