Question

我在这里问了一个上一个问题，得到了很好的反馈。我在同一个程序中又回来了一个问题。我的输出文件总是空白，我弄清楚原因，但我不知道如何纠正它。在getArray中，我将totalEmployees设置为stage2 textField中输入的值。这应该是数组大小声明，但是当我测试代码时，数组大小总是设置为0，因此给我一个空白文本doc。这是因为在将值保存到totalEmployees之前，数组大小设置为totalEmployees。我不太清楚如何纠正这个问题。这是我的代码：

import java.io.*;

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

public class companyParoll extends Application 
{
    private TextField tfNumOfEmployees = new TextField();
    private TextField tfEmpFirstName = new TextField();
    private TextField tfEmpLastName = new TextField();
    private TextField tfEmpPayRate = new TextField();
    private TextField tfEmpHoursWorked = new TextField();
    private Button btEnterNum = new Button("Submit");
    private Button btNextEmp = new Button("Add Employee");
    private Button btRunReport = new Button("Run Report");
    private Button btQuit = new Button("Quit");

    //Declare Variables
    int totalEmployees;
    int index = 0;
    String[] firstName = new String[totalEmployees];
    String[] lastName = new String[totalEmployees];
    double[] payRate = new double[totalEmployees];
    double[] hoursWorked = new double[totalEmployees];
    Stage stage2 = new Stage();

    @Override // Override the start method in the Application class
    public void start(Stage primaryStage)
    {
        //Create the UI
        GridPane gridPane =new GridPane();
        GridPane gridPane2 = new GridPane();
        gridPane.setHgap(75);
        gridPane.setVgap(15);
        gridPane.add(new Label("Employee's First Name:"), 0, 0);
        gridPane.add(tfEmpFirstName, 1, 0);
        gridPane.add(new Label("Employee's Last Name:"), 0, 1);
        gridPane.add(tfEmpLastName, 1, 1);
        gridPane.add(new Label("Employee's Hourly Pay Rate:"), 0, 2);
        gridPane.add(tfEmpPayRate, 1, 2);
        gridPane.add(new Label("Hours Worked by Employee"), 0, 3);
        gridPane.add(tfEmpHoursWorked, 1, 3);
        gridPane.add(btNextEmp, 1, 4);
        gridPane.add(btQuit, 0, 6);
        gridPane.add(btRunReport, 1, 6);

        //Set properties
        gridPane.setAlignment(Pos.CENTER);
        tfEmpFirstName.setAlignment(Pos.BOTTOM_RIGHT);
        tfEmpLastName.setAlignment(Pos.BOTTOM_RIGHT);
        tfEmpPayRate.setAlignment(Pos.BOTTOM_RIGHT);
        tfEmpHoursWorked.setAlignment(Pos.BOTTOM_RIGHT);
        GridPane.setHalignment(btQuit, HPos.LEFT);
        GridPane.setHalignment(btRunReport, HPos.RIGHT);
        GridPane.setHalignment(btNextEmp, HPos.RIGHT);

        gridPane2.setHgap(75);
        gridPane2.setVgap(15);
        gridPane2.add(new Label("Enter the Number of Employees:"), 0, 0);
        gridPane2.add(tfNumOfEmployees,0 ,1);
        gridPane2.add(btEnterNum, 0, 2);

        gridPane2.setAlignment(Pos.CENTER);
        tfNumOfEmployees.setAlignment(Pos.BOTTOM_RIGHT);
        GridPane.setHalignment(btEnterNum, HPos.CENTER);    

        btEnterNum.setOnAction(e -> getArraySize());
        btRunReport.setOnAction(e -> outputReport());
        btNextEmp.setOnAction(e -> addEmployeeData());
        btQuit.setOnAction(e -> quitApplication());

        // Create a scene and place it in the stage
        Scene scene= new Scene(gridPane, 400, 250) ;
        primaryStage.setTitle("Payroll Calculator"); // Set title
        primaryStage.setScene(scene); // Place the scene in t he stage
        primaryStage.show(); // Display the stage   

        //Create new window to get number of employees
        Scene scene2 = new Scene(gridPane2, 200, 150);
        stage2.setTitle("Number of Employees");
        stage2.setScene(scene2);
        stage2.show();
    }

    public void getArraySize()
    {
        totalEmployees = Integer.parseInt(tfNumOfEmployees.getText());
        stage2.close();
    }

    public void addEmployeeData()
    {
        while (index < firstName.length)
        {
            firstName[index] = tfEmpFirstName.getText();
            lastName[index] = tfEmpLastName.getText();
            payRate[index] = Double.parseDouble(tfEmpPayRate.getText());
            hoursWorked[index] = Integer.parseInt(tfEmpHoursWorked.getText());

            index ++;
            break;
        }

        tfEmpFirstName.clear();
        tfEmpLastName.clear();
        tfEmpPayRate.clear();
        tfEmpHoursWorked.clear();
    }

    public void outputReport()
    {
        try
        {
            PrintWriter empPayroll = new PrintWriter("Payroll.txt");

            double regularHours = 0;
            double overtimeHours = 0;
            double regularPay = 0;
            double overtimePay = 0;
            double totalPay = 0;

            for (index = 0; index < firstName.length; index++)
            {
                if (hoursWorked[index] >= 40)
                    regularHours = 40;
                else
                    regularHours = hoursWorked[index];

                if (hoursWorked[index] > 40)
                    overtimeHours = hoursWorked[index] - 40;
                else
                    overtimeHours = 0;

                regularPay = (payRate[index] * regularHours);

                overtimePay = ((payRate[index] * 1.5) * overtimeHours);

                totalPay = regularPay + overtimePay;

                empPayroll.println("\nName: " + firstName[index] + " " + lastName[index]);
                empPayroll.println("Pay Rate: " + payRate[index]);
                empPayroll.println("Regular Hours Worked: " + regularHours);
                empPayroll.println("Overtime Hours Worked: " + overtimeHours);
                empPayroll.println("Regular Pay: " + regularPay);
                empPayroll.println("Overtime Pay: " + overtimePay);
                empPayroll.println("Total Gross Pay: " + totalPay);
            }

            empPayroll.close();            
        } 
        catch (IOException exp)
        {
            exp.printStackTrace();
        }
System.out.println(firstName.length);
    }

    public void quitApplication()
    {
        Platform.exit(); //Close application
    }

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

Answer 1

看起来你只是使用“totalEmployees”来实例化那些数组。假设在用户点击btEnterNum之前不会使用这些数组（这很重要，因为尝试这样做会导致Null Pointer Exception），您可以声明数组，并在getArraySize()方法中实例化它们。

private String[] firstName;
private String[] lastName;
private double[] payRate;
private double[] hoursWorked;

public void getArraySize() {
    totalEmployees = Integer.parseInt(tfNumOfEmployees.getText());

    firstName = new String[totalEmployees];
    lastName = new String[totalEmployees];
    payRate = new double[totalEmployees];
    hoursWorked = new double[totalEmployees];

    stage2.close();
}

但另一方面，如果您确实需要先使用这些数组，那么您可以尝试使用ArrayList。 HTH

数组大小未正确设置

1 个答案: