JFX 7.4

package divisible.by.pkg3;

import javafx.scene.control.*;
import javafx.application.Application;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

/**
 *
 * @author Monty
 */
public class DivisibleBy3 extends Application {
private TextField tfNum = new TextField();
private TextField tfOut = new TextField();
private Label lblOut = new Label();
private Button btCheck = new Button("Check");
private String end;

    @Override
    public void start(Stage stage1) {
        GridPane gp = new GridPane();
        gp.setHgap(5);
        gp.setVgap(5);
        gp.add(new Label("Enter int:"),0,0);
        gp.add(tfNum,1,0);
        gp.add(btCheck,0,1);
        gp.add(lblOut,1,1);

        btCheck.setOnAction(e -> checkInt());



        Scene scene = new Scene(gp, 300,100);
        stage1.setTitle("Divisible By 3");
        stage1.setScene(scene);
        stage1.show();
    }

    private void checkInt(){
        int num = Integer.parseInt(tfNum.getText());
        if(num%3 == 0){
            end = "Number is divisible by 3.";

        } else {
            end = "Number is not divisible by 3.";
           // gp.add(new Label(end),1,1);
        }

        lblOut.setText(end);
    }

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

}