How to add multiple lines of text to a text area using javafx?

Question

I am using javafx to create a pane that asks for Loan Amount and Number of Years to calculate how much the monthly and total payment will be based on an annual interest rate increasing by .125 from 5% to 8%.

I want to print this out in the form of a table below the initial pane. However, I am stuck trying to figure how to add multiple lines of text to a text area variable.

Here's my code:

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.FlowPane;
import javafx.scene.layout.BorderPane;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.control.TextArea;


public class LoanTable extends Application {

    // create TextField and button variables
    private TextField tfAmount = new TextField();
    private TextField tfYears = new TextField();
    private Button btCalc = new Button("Show Table");
    private TextArea taResult = new TextArea();

    @Override
    public void start(Stage primaryStage) {

        // create FlowPane and set properties
        FlowPane pane = new FlowPane();
        pane.setHgap(10);
        tfAmount.setPrefColumnCount(3);
        tfYears.setPrefColumnCount(3);
        pane.getChildren().addAll(new Label("Loan Amount"), tfAmount, new Label("Number of Years"), tfYears, btCalc);

        // create ScrollPane and set properties
        ScrollPane scrollPane = new ScrollPane(taResult);
        taResult.setEditable(false);


        // create BorderPane and add FlowPane and ScrollPane
        BorderPane borderPane = new BorderPane();
        borderPane.setCenter(pane);
        borderPane.setBottom(scrollPane);

        // create and register a handler
        btCalc.setOnAction(e -> calcTable());

        // create a scene and place it in the stage
        Scene scene = new Scene(borderPane);
        primaryStage.setTitle("Loan-Table");
        primaryStage.setScene(scene);
        primaryStage.show();

    }

    // create a method to calculate monthly payment
    public double calcMonthly(double interestRate) {
        double loanAmount = Double.parseDouble(tfAmount.getText());
        int years = Integer.parseInt(tfYears.getText());
        double monthlyInterestRate = interestRate / 1200;
        double monthlyPayment = loanAmount * monthlyInterestRate / (1 - 1 / Math.pow(1 + monthlyInterestRate, years * 12));

        return monthlyPayment;
        }

    // create a method to calculate total payment
    public double calcTotal(double interestRate, double monthlyPayment) {
        int years = Integer.parseInt(tfYears.getText());
        double totalPayment = monthlyPayment * years * 12;

        return totalPayment;
        }

    private void calcTable() {
        // get values from text fields
        double interestRate = 5;

        // display table header
        taResult.setText(String.format("%13s%20s%18s\n", "Interest Rate", "Monthly Payment", "Total Payment"));

        // print rest of table
        for (int i = 1; i < 26; interestRate+=.125, i++) {
            double x = calcMonthly(interestRate);
            taResult.setText(String.format("%5.3f%19.2f%22.2f\n", interestRate, calcMonthly(interestRate), calcTotal(interestRate, x)));
        }
    }


    public static void main(String args[]) {

        Application.launch(args);

    }

}

The issue comes at the "// print rest of the table" loop. How do I add multiple lines of text to the taResult variable? When I run this program, I just end up with the last line of the table. With inputs 10000 (for Loan Amount) and 5 (for Number of Years) the output is:

8.000             202.76              12165.84

But my desired output is:

Interest Rate     Monthly Payment     Total Payment
5.000             188.71              11322.74
5.125             189.29              11357.13
5.250             189.86              11391.59
5.375             190.44              11426.11
5.500             191.01              11460.70
5.625             191.59              11495.35
5.750             192.17              11530.06
5.875             192.75              11564.84
6.000             193.33              11599.68
6.125             193.91              11634.59
6.250             194.49              11669.56
6.375             195.08              11704.59
6.500             195.66              11739.69
6.625             196.25              11774.85
6.750             196.83              11810.08
6.875             197.42              11845.37
7.000             198.01              11880.72
7.125             198.60              11916.14
7.250             199.19              11951.62
7.375             199.79              11987.16
7.500             200.38              12022.77
7.625             200.97              12058.44
7.750             201.57              12094.18
7.875             202.17              12129.97
8.000             202.76              12165.84

I hope I made the issue clear.

Answer 1

Ah, nevermind. I figured it out.

I needed taResult.appendText --- .appendText is what I was looking for.

Sorry for wasting anyone's time that was reading this.