JavaFX TextField create a loan calculator

import javafx.application.Application;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class Main extends Application {
   @Override//from ww w .j  a  v a  2  s. c om
   public void start(Stage primaryStage) {
      Text tInvestmentAmount = new Text("Investment Amount:");
      Text tNumberOfYears = new Text("Number of Years:");
      Text tAnnualInterestRate = new Text("Annual Interest Rate:");
      Text tFutureValue = new Text("Future Value:");

      TextField tfInvestmentAmount = new TextField();
      TextField tfNumberOfYears = new TextField();
      TextField tfAnnualInterestRate = new TextField();
      TextField tfFutureValue = new TextField();
      tfFutureValue.setEditable(false);

      Button btCalculate = new Button("Calculate");
      btCalculate.setOnAction(e -> {
         double a = getDoubleFromTextField(tfInvestmentAmount);
         double b = getDoubleFromTextField(tfAnnualInterestRate) / 1200;
         double c = getDoubleFromTextField(tfNumberOfYears) * 12;
         tfFutureValue.setText(String.format("$%.2f", a * Math.pow(1 + b, c)));
      });

      GridPane pane = new GridPane();
      pane.addRow(0, tInvestmentAmount, tfInvestmentAmount);
      pane.addRow(1, tNumberOfYears, tfNumberOfYears);
      pane.addRow(2, tAnnualInterestRate, tfAnnualInterestRate);
      pane.addRow(3, tFutureValue, tfFutureValue);
      pane.add(btCalculate, 1, 4);
      pane.setVgap(5);
      pane.setHgap(5);
      pane.setPadding(new Insets(5));
      GridPane.setHalignment(btCalculate, HPos.RIGHT);
      pane.setAlignment(Pos.CENTER);

      Scene scene = new Scene(pane);
      primaryStage.setTitle("java2s.com");
      primaryStage.setScene(scene);
      primaryStage.show();
   }

   private static double getDoubleFromTextField(TextField t) {
      return Double.parseDouble(t.getText());
   }

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