package appcalculator;

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

public class AppCalculator extends Application {

@Override
public void start(Stage stage) throws Exception {
    Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));

    Scene scene = new Scene(root);

    stage.setScene(scene);
    stage.show();
}

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

}

package appcalculadora;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.TextField;

public class FXMLDocumentController implements Initializable {


TextField texto = new TextField();


@FXML
private void btnOne(ActionEvent event) {
    texto.setText("1");

}

@FXML
private void btnTwo(ActionEvent event) {
    texto.setText("2");
}

@FXML
private void btnThree(ActionEvent event) {
    texto.setText("3");
}

@FXML
private void btnFour(ActionEvent event) {
    texto.setText("4");
}

@FXML
private void btnFive(ActionEvent event) {
    texto.setText("5");
}

@FXML
private void btnSix(ActionEvent event) {
    texto.setText("6");
}

@FXML
private void btnSevent(ActionEvent event) {
    texto.setText("7");
}

@FXML
private void btnEight(ActionEvent event) {
    texto.setText("8");
}

@FXML
private void btnNine(ActionEvent event) {
    texto.setText("9");
}

@FXML
private void btnZero(ActionEvent event) {
    texto.setText("0");
}

@FXML
private void btnPoint(ActionEvent event) {
    texto.setText(".");
}

@FXML
private void btnPlus(ActionEvent event) {
    texto.setText("+");
}

@FXML
private void btnMinus(ActionEvent event) {
    texto.setText("-");
}

@FXML
private void btnBy(ActionEvent event) {
    texto.setText("*");
}

@FXML
private void btnDivided(ActionEvent event) {
    texto.setText("/");
}

@FXML
private void btnErrase(ActionEvent event){
    texto.deletePreviousChar();
}

@FXML
private void btnTotal(ActionEvent event){
    texto.getText();
}

@Override
public void initialize(URL url, ResourceBundle rb) {
    // TODO
}

}