JavaFX the tip calculator in the below code is not staying in the limits of 0% - 30% by whole number (whole percent).

The total is automatically being made, and has to be that way. If the Amount can be change after the initial input, that would be great, too.

3 files, TipCalculator.java, TipCalculatorController.java, TipCalculator.FXML

The only changes should be near the bottom of the controller, missing the TipCalculatorController.percent feature, and possibly something in the FXML file.

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TipCalculator.java

package application;

//Fig. 12.19: TipCalculator.java

//Main application class that loads and displays the Tip Calculator's GUI.

import javafx.application.Application;

import javafx.fxml.FXMLLoader;

import javafx.scene.Parent;

import javafx.scene.Scene;

import javafx.stage.Stage;

public class TipCalculator extends Application {

@Override

public void start(Stage stage) throws Exception {

Parent root =

FXMLLoader.load(getClass().getResource("TipCalculator.fxml"));

Scene scene = new Scene(root); // attach scene graph to scene

stage.setTitle("Tip Calculator"); // displayed in window's title bar

stage.setScene(scene); // attach scene to stage

stage.show(); // display the stage

}

public static void main(String[] args) {

// create a TipCalculator object and call its start method

launch(args);

}

}

TipCalculatorController.java

package application;

//TipCalculatorController.java

//Controller that handles calculateButton and tipPercentageSlider events

import java.math.BigDecimal;

import java.math.RoundingMode;

import java.text.NumberFormat;

import javafx.beans.value.ChangeListener;

import javafx.beans.value.ObservableValue;

import javafx.event.ActionEvent;

import javafx.fxml.FXML;

import javafx.scene.control.Label;

import javafx.scene.control.Slider;

import javafx.scene.control.TextField;

public class TipCalculatorController {

// formatters for currency and percentages

private static final NumberFormat currency =

NumberFormat.getCurrencyInstance();

private static final NumberFormat percent =

NumberFormat.getPercentInstance();

private BigDecimal tipPercentage = new BigDecimal(0.15); // 15% default

// GUI controls defined in FXML and used by the controller's code

@FXML

private TextField amountTextField;

@FXML

private Label tipPercentageLabel;

@FXML

private Slider tipPercentageSlider;

@FXML

private TextField tipTextField;

@FXML

private TextField totalTextField;

// calculates and displays the tip and total amounts

@FXML

private void calculateButtonPressed(ActionEvent event) {

try {

BigDecimal amount = new BigDecimal(amountTextField.getText());

BigDecimal tip = amount.multiply(tipPercentage);

BigDecimal total = amount.add(tip);

tipTextField.setText(currency.format(tip));

totalTextField.setText(currency.format(total));

}

catch (NumberFormatException ex) {

amountTextField.setText("Enter amount");

amountTextField.selectAll();

amountTextField.requestFocus();

}

}

// called by FXMLLoader to initialize the controller

public void initialize() {

// 0-4 rounds down, 5-9 rounds up

currency.setRoundingMode(RoundingMode.HALF_UP);

// listener for changes to tipPercentageSlider's value

tipPercentageSlider.valueProperty().addListener(

new ChangeListener() {

@Override

public void changed(ObservableValue ov,

Number oldValue, Number newValue) {

tipPercentage =

BigDecimal.valueOf(newValue.intValue() / 100.0);

tipPercentageLabel.setText(percent.format(tipPercentage));

}

}

);

}

}

TipCalculator.fxml