java - Javafx 应用程序不会运行只是构建和构建失败
问题描述
我目前正在开发一个计算每月还款额的应用程序。我从我的其他程序中获取代码来制作我想要的东西,我相信我拥有执行它所需的一切,但构建失败,我不知道为什么。Javafx 是我的新手,所以我很想了解更多关于它的信息,但可以使用一些方向来解决我的错误
我曾尝试与以前的程序逐行进行,但没有看到任何差异,因此不确定为什么会出现错误。也有同学看一下帮助调试
package project2a;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.control.TitledPane;
import javafx.scene.layout.VBox;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
/**
*
* @author Carmine , Eric , Rohit
*/
public class Project2a extends Application {
//Text fields for loan amount
TextField tfLoanAmount = new TextField();
TextField tfInterestRate= new TextField();
TextArea textArea = new TextArea();
//Radio buttons for years
private RadioButton rbOneYear;
private RadioButton rbTwoYear;
private RadioButton rbFiveYear;
private RadioButton rbSevenYear;
private RadioButton rbTenYear;
private RadioButton rbFifteenYear;
private ToggleGroup group;
private Button btnCalculate;
//labels for output
private Label lblMonthlyPayment;
private Label lblHeader;
private Label lblYears;
//vbox for layout of items
private VBox vBoxRadio;
private VBox vBoxInputs;
private VBox vBoxResults;
private TitledPane titledPaneRadio;
@Override
public void start(Stage primaryStage)
{
//makes header
lblHeader= new Label("Calculate your monthly loan payment!");
lblHeader.setMinWidth(350);
lblHeader.setAlignment(Pos.CENTER);
lblHeader.setStyle("-fx-font-family: 'Comic Sans MS'; -fx-font-size: 28px; -fx-text-fill: white; -fx-background-color: rgb(104, 50, 0); -fx-font-weight: bold;");
EventHandler<ActionEvent> handler = event -> updateRates();
tfLoanAmount.setOnAction(handler);
tfInterestRate.setOnAction(handler);
TextField tfLoanAmount = new TextField();
rbOneYear= new RadioButton("One Years");
rbTwoYear= new RadioButton("Two Years");
rbFiveYear= new RadioButton("Five Years");
rbSevenYear= new RadioButton("Seven Years");
rbTenYear= new RadioButton("Ten Years");
rbFifteenYear= new RadioButton("Fifteen Years");
group = new ToggleGroup();
group.getToggles().addAll(rbOneYear, rbTwoYear, rbFiveYear, rbSevenYear, rbTenYear, rbFifteenYear);
rbFiveYear.setSelected(true);
vBoxRadio = new VBox(20,rbOneYear, rbTwoYear, rbFiveYear, rbSevenYear, rbTenYear, rbFifteenYear);
vBoxRadio.setPadding( new Insets(10) );
titledPaneRadio = new TitledPane("Number of Years", vBoxRadio);
vBoxInputs = new VBox(0, titledPaneRadio);
//creates calculate button
btnCalculate = new Button(" Calculate ");
btnCalculate.setStyle("-fx-text-fill: white; -fx-background-color: tan; -fx-font-weight: bold;");
btnCalculate.setOnAction( e -> calculateMonthlyPayment(e) );
lblYears= new Label("Number of Years: \t");
vBoxResults = new VBox(50, lblMonthlyPayment, btnCalculate);
vBoxResults.setPrefWidth(140);
vBoxResults.setPrefHeight(270);
vBoxResults.setPadding( new Insets(10) );
vBoxResults.setStyle("-fx-background-color: cornsilk; -fx-border-color: black; -fx-border-radius: 10;");
GridPane grid = new GridPane();
grid.addRow(0, lblHeader);
GridPane.setColumnSpan(lblHeader, 2);
GridPane.setHalignment(lblHeader, HPos.CENTER);
grid.addRow(1, vBoxInputs, vBoxResults);
Scene scene = new Scene(grid, 350, 310);
primaryStage.setTitle("Loan Payment Calculator");
primaryStage.setResizable(false);
primaryStage.setScene(scene);
primaryStage.show();
}
private void updateRates() {
double annualInterestRate = 5.00;
double loanAmount = Double.parseDouble(tfLoanAmount.getText());
double numberOfYears = Double.parseDouble(lblYears.getText());
String s = String.format("%-1s%20s%20s\n", "Interest Rate", "Monthly Payment", "Total Payment");
// making loop to display different interest rates
for ( ; annualInterestRate <= 8.00; annualInterestRate += 0.125) {
// calculating monthly and total payment rates
double monthlyInterestRate = annualInterestRate / 1200;
double monthlyPayment = loanAmount * monthlyInterestRate / (1 - 1 / Math.pow(1 + monthlyInterestRate, numberOfYears * 12));
double totalPayment = monthlyPayment * numberOfYears * 12;
// making % string for formatting reasons...
String str = "%";
// Displaying formatted info
s += String.format("%-1.3f%s%19.2f%30.2f \n", annualInterestRate, str, ((int) (monthlyPayment * 100) / 100.0), ((int) (totalPayment * 100) / 100.0));
}
textArea.setText(s);
}
private void calculateMonthlyPayment(ActionEvent e)
{
int years=0;
if(rbOneYear.isSelected())
{
years=1;
}
else if(rbTwoYear.isSelected())
{
years=2;
}
else if(rbFiveYear.isSelected())
{
years=5;
}
else if (rbSevenYear.isSelected())
{
years=7;
}
else if(rbTenYear.isSelected())
{
years=10;
}
else if(rbTenYear.isSelected())
{
years=10;
}
lblYears.setText("Year(s) Selected: " + years);
lblMonthlyPayment.setText("Monthly Payment: " );
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
}
预期的是贷款年数的 6 个单选按钮,显示在侧面板标签中的年份,输入贷款金额和利率的文本字段供用户输入,它也显示在侧面板上用于计算。还有一些颜色等,让它对用户来说看起来不错
解决方案
异常抛出vBoxResults = new VBox(50, lblMonthlyPayment, btnCalculate);
您的问题是将未初始化(null)添加lblMonthlyPayment
到 VBox 中,因此初始化lblMonthlyPayment
并且这将修复您的应用程序并且它将毫无问题地运行
参考下文,
lblYears = new Label("Number of Years: \t");
lblMonthlyPayment = new Label("");
vBoxResults = new VBox(50, lblMonthlyPayment, btnCalculate);
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