I have the following code and need to figure out how to display an error message using exception handling when the user does not enter numeric values for loan amount or years.

package project;

import javafx.application.Application;

import javafx.event.ActionEvent;

import javafx.scene.Scene;

import javafx.stage.Stage;

import javafx.scene.control.Label;

import javafx.scene.control.TextField;

import javafx.scene.control.TextArea;

import javafx.scene.control.Button;

import javafx.scene.control.ScrollPane;

import javafx.scene.layout.HBox;

import javafx.scene.layout.BorderPane;

import javafx.geometry.Pos;

public class loanTable extends Application {

protected TextField tfLoanAmount = new TextField();

protected TextField tfNumberOfYears = new TextField();

protected TextArea textArea = new TextArea();

}

@Override //

public void start(Stage primaryStage) {

tfNumberOfYears.setPrefColumnCount(2);

tfLoanAmount.setPrefColumnCount(7);

textArea.setPrefColumnCount(30);

Button btShowTable = new Button("Show Table");

HBox paneForControls = new HBox(10);

paneForControls.setAlignment(Pos.CENTER);

paneForControls.getChildren().addAll(new Label("Loan Amount"), tfLoanAmount,

new Label("Number of Years"), tfNumberOfYears, btShowTable);

ScrollPane scrollPane = new ScrollPane(textArea);

BorderPane pane = new BorderPane();

pane.setTop(paneForControls);

pane.setCenter(textArea);

btShowTable.setOnAction(e -> {

print();

});

Scene scene = new Scene(pane);

primaryStage.setTitle("Exercise_16_13");

primaryStage.setScene(scene);

primaryStage.show();

}

private void print() {

String output = "";

double monthlyInterestRate;

double monthlyPayment;

for (double i = 5.0; i <= 8; i += 0.125) {

monthlyInterestRate = i / 1200;

monthlyPayment = Double.parseDouble(tfLoanAmount.getText()) *

monthlyInterestRate / (1 - 1 / Math.pow(1 + monthlyInterestRate,

Double.parseDouble(tfNumberOfYears.getText()) * 12));

output += String.format("%-24.3f%-34.2f%-8.2f ", i,

monthlyPayment, (monthlyPayment * 12) *

Double.parseDouble(tfNumberOfYears.getText()));

}

textArea.setText(output);

}

public static void main(String args[]) {

launch(args);

}

}