Question

please help me debug this

Create a Future Value Calculator that displays error messages in labels.GUISpecificationsStart with the JavaFX version of the Future Value application presented in chapter 17. Create error message labels for each text field that accepts user input. Use the Validation class from chapter 17 to validate user input.Format the application so that the controls don’t change position when error messages are displayed.

package murach.business;

public class Calculation {
  
    public static final int MONTHS_IN_YEAR = 12;

    public static double futureValue(double monthlyPayment,
            double yearlyInterestRate, int years) {
      
        int months = years * MONTHS_IN_YEAR;
        double monthlyInterestRate = yearlyInterestRate / MONTHS_IN_YEAR / 100;
        double futureValue = 0;
        for (int i = 1; i <= months;) {
            futureValue = (futureValue + monthlyPayment)
                    * (1 + monthlyInterestRate);
        }
        return futureValue;
    }
}

/***********************************************************************************

package murach.business;

public class Validation {
    private String lineEnd;
  
    public Validation() {
        this.lineEnd = "\n";
    }
    public Validation(String lineEnd) {
        this.lineEnd = lineEnd;
    }
  
    public String isPresent(String value, String name) {
        String msg = "";
        if (value.isEmpty()) {
            msg = name + " is required." + lineEnd;
        }
        return msg;
    }
  
    public String isDouble(String value, String name) {
        String msg = "";
         {
            Double.parseDouble(value);
        } catch (NumberFormatException e) {
            msg = name + " must be a valid number." + lineEnd;
        }
        return msg;
    }
  
    public String isInteger(String value, String name) {
        String msg = "";
        try {
            Integer.parseInt(value);
        } catch (NumberFormatException e) {
            msg = name + " must be an integer." + lineEnd;
        }
        return msg;
    }
}
/**************************************************************************************************************

package murach.ui;

import murach.business.Validation;
import murach.business.Calculation;
import java.text.NumberFormat;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class FutureValueApp extends Application {
    private TextField investmentField;
    private TextField interestRateField;
    private TextField yearsField;
    private TextField futureValueField;
  
    private Label investmentLabel;
    private Label interestRateLabel;
    private Label yearsLabel;
      
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Future Value Calculator");
      
        GridPane grid = new GridPane();
        grid.setAlignment(Pos.TOP_LEFT);
        grid.setPadding(new Insets(25, 25, 25, 25));
        grid.setHgap(10);
        grid.setVgap(10);

        Scene scene = new Scene(grid, 580, 220);
      
        grid.add(new Label("Monthly Investment:"), 0, 0);
        investmentField = new TextField();
        grid.add(investmentField, 1, 0);
        investmentLabel = new Label();
        grid.add(investmentLabel, 2, 0);

        grid.add(new Label("Yearly Interest Rate:"), 0, 1);
        interestRateField = new TextField();
        grid.add(interestRateField, 1, 1);
        interestRateLabel = new Label();
        grid.add(interestRateLabel, 2, 1);
      
        grid(new Label("Years:"), 0, 2);
        yearsField = new TextField();
        grid.add(yearsField, 1, 2);
        yearsLabel = new Label();
        grid.add(yearsLabel, 2, 2);
      
        grid.add(new Label("Future Value:"), 0, 3);
        futureValueField = new TextField();
        futureValueField.setEditable(false);
        grid.add(futureValueField, 1, 3);

        calculateButton = new Button("Calculate");
        calculateButton.setOnAction(event -> calculateButtonClicked());
      
        Button exitButton = new Button("Exit");
        exitButton.setOnAction(event -> exitButtonClicked());
      
        HBox buttonBox = new HBox(10);
        buttonBox.getChildren().add(calculateButton);
        buttonBox.getChildren().add(exitButton);
        buttonBox.setAlignment(Pos.BOTTOM_RIGHT);
        grid.add(buttonBox, 0, 4, 2, 1);
             
        primaryStage.setScene();
        primaryStage.show();
    }
  
    private void calculateButtonClicked() {
        // set error messages in labels
        Validation v = new Validation();
        investmentLabel.setText(
            v.isDouble(investmentField.getText(), "Monthly Investment") );      
        interestRateLabel.setText(
            v.isDouble(interestRateField.getText(), "Yearly Interest Rate") );      
        yearsLabel.setText( v.isDouble(yearsField.getText(), "Years") );
      
        // check if all error labels are empty
        if (investmentLabel.getText().isEmpty() &&
            interestRateLabel.getText().isEmpty() &&
            yearsLabel.getText().isEmpty()) {

            // get data from text fields
            double investment = Double.parseDouble(investmentField.getText());
            double rate = Double.parseDouble(interestRateField.getText());
            int years = Integer.parseInt(yearsField.getText());

            // calculate future value
            double futureValue = Calculation.futureValue(investment, rate, years);

            // set data in read-only text field
            NumberFormat currency = NumberFormat.getCurrencyInstance();
            futureValueField.setText(currency.format(futureValue));
        }      
    }

    private void exitButtonClicked() {
        System.exit(0);   // 0 indicates a normal exit
    }
  
    public static void main(String[] args) {
        launch(args);
    }     
}

Answer 1

Below is the solution:

There was some error in code its corrected.

import java.text.NumberFormat;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class FutureValueApp extends Application {
   private TextField investmentField;
   private TextField interestRateField;
   private TextField yearsField;
   private TextField futureValueField;

   private Label investmentLabel;
   private Label interestRateLabel;
   private Label yearsLabel;

   @Override
   public void start(Stage primaryStage) {
       primaryStage.setTitle("Future Value Calculator");

       GridPane grid = new GridPane();
       grid.setAlignment(Pos.TOP_LEFT);
       grid.setPadding(new Insets(25, 25, 25, 25));
       grid.setHgap(10);
       grid.setVgap(10);

       Scene scene = new Scene(grid, 580, 220);

       grid.add(new Label("Monthly Investment:"), 0, 0);
       investmentField = new TextField();
       grid.add(investmentField, 1, 0);
       investmentLabel = new Label();
       grid.add(investmentLabel, 2, 0);

       grid.add(new Label("Yearly Interest Rate:"), 0, 1);
       interestRateField = new TextField();
       grid.add(interestRateField, 1, 1);
       interestRateLabel = new Label();
       grid.add(interestRateLabel, 2, 1);

       grid.add(new Label("Years:"), 0, 2);
       yearsField = new TextField();
       grid.add(yearsField, 1, 2);
       yearsLabel = new Label();
       grid.add(yearsLabel, 2, 2);

       grid.add(new Label("Future Value:"), 0, 3);
       futureValueField = new TextField();
       futureValueField.setEditable(false);
       grid.add(futureValueField, 1, 3);

       Button calculateButton = new Button("Calculate");
       calculateButton.setOnAction(event -> calculateButtonClicked());

       Button exitButton = new Button("Exit");
       exitButton.setOnAction(event -> exitButtonClicked());

       HBox buttonBox = new HBox(10);
       buttonBox.getChildren().add(calculateButton);
       buttonBox.getChildren().add(exitButton);
       buttonBox.setAlignment(Pos.BOTTOM_RIGHT);
       grid.add(buttonBox, 0, 4, 2, 1);

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

   private void calculateButtonClicked() {
       //set the label to empty
       investmentLabel.setText("");
       interestRateLabel.setText("");
       yearsLabel.setText("");
       //// set error messages in labels
       Validation v = new Validation();
       investmentLabel.setText(v.isDouble(investmentField.getText(), "Monthly Investment"));
       interestRateLabel.setText(v.isDouble(interestRateField.getText(), "Yearly Interest Rate"));
       yearsLabel.setText(v.isInteger(yearsField.getText(), "Years"));
       //check if all error labels are empty
       if (investmentLabel.getText().isEmpty() && interestRateLabel.getText().isEmpty() && yearsLabel.getText().isEmpty()) {
           // get data from text fields
           double investment = Double.parseDouble(investmentField.getText());
           double rate = Double.parseDouble(interestRateField.getText());
           int years = Integer.parseInt(yearsField.getText());

           // calculate future value
           double futureValue = Calculation.futureValue(investment, rate, years);

           // set data in read-only text field
           NumberFormat currency = NumberFormat.getCurrencyInstance();
           futureValueField.setText(currency.format(futureValue));
       }
   }

   private void exitButtonClicked() {
       System.exit(0); // 0 indicates a normal exit
   }

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

public class Calculation {
   public static final int MONTHS_IN_YEAR = 12;

   public static double futureValue(double monthlyPayment, double yearlyInterestRate, int years) {
       int months = years * MONTHS_IN_YEAR;
       double monthlyInterestRate = yearlyInterestRate / MONTHS_IN_YEAR / 100;
       double futureValue = 0;
       for (int i = 1; i <= months; i++) { //i increment was missing
           futureValue = (futureValue + monthlyPayment) * (1 + monthlyInterestRate); //calculate the future value by formula
       }
       return futureValue;
   }
}

public class Validation {
   private String lineEnd;

   public Validation() {
       this.lineEnd = "\n";
   }

   public Validation(String lineEnd) {
       this.lineEnd = lineEnd;
   }

   public String isPresent(String value, String name) {
       String msg = "";
       if (value.isEmpty()) {
           msg = name + " is required." + lineEnd;
       }
       return msg;
   }

   public String isDouble(String value, String name) {
       String msg = "";
       try {
           Double.parseDouble(value);
       } catch (NumberFormatException e) {
           msg = name + " must be a valid number." + lineEnd;
       }
       return msg;
   }

   public String isInteger(String value, String name) {
       String msg = "";
       try {
           Integer.parseInt(value);
       } catch (NumberFormatException e) {
           msg = name + " must be an integer." + lineEnd;
       }
       return msg;
   }
}

sample output: