Question

我是Java的新手。我这个学期正在上网。我们使用的这本书并不是最好的。我试着在网上寻找答案，但我很快就会出现问题。也许你们中的一个人可以帮助我：）

基本上，下面的程序假定提示用户输入信息，程序然后计算扣除并将信息输出到.txt文件。它运行并遵守，没有错误。弹出对话框，但没有数据写入文件。 .txt文件保存在同一个文件夹中。有什么想法吗？

import java.io.*;
import java.util.*;
import javax.swing.JOptionPane;

public class PaycheckCalculator
{

    static final double FEDERAL_TAX = .15, STATE_TAX = .035, SOCIAL_SECURITY = .0575, MEDICARE_MEDICAID = .0275,PENSION = .05;
    static final int HEALTH_INSURANCE = 75;

    public static void main (String[] args) throws FileNotFoundException
    {

        String employeeName;
        String inputStr;

        double grossPay, netPay, federal, state, social, medicare, pension;
        int healthInsurance;

        PrintWriter outFile = new PrintWriter ("paycalc.txt");


        employeeName = JOptionPane.showInputDialog ("Please enter your name: ");

        inputStr = JOptionPane.showInputDialog ("Please enter your monthly gross pay: ");
        grossPay = Double.parseDouble (inputStr);

        federal = (grossPay * FEDERAL_TAX);
        state = (grossPay * STATE_TAX);
        social = (grossPay * SOCIAL_SECURITY);
        medicare = (grossPay * MEDICARE_MEDICAID);
        pension = (grossPay * PENSION);


        netPay = (grossPay - federal - state - social - medicare - pension - HEALTH_INSURANCE);

        outFile.println (employeeName);
        outFile.printf ("Gross Amount: %.2f%n", grossPay);
        outFile.printf ("Federal Tax: %.2f%n", federal);
        outFile.printf ("State Tax: %.2f%n", state);
        outFile.printf ("Social Security Tax: %.2f%n", social);
        outFile.printf ("Medicare\\Medicaid Tax: %.2f%n", medicare);
        outFile.printf ("Pension Plan: %.2f%n", pension);
        outFile.printf ("Health Insurance: $" + HEALTH_INSURANCE);
        outFile.printf ("Net Pay: %.2f%n", netPay);


        System.exit(0);
        outFile.close();

    }
}

Answer 1

您必须在申请退出前关闭PrintWriter。

您可以删除System.exit(0);行（无用）或在close()操作后放置。

这样，在应用程序退出之前，数据将被刷新到paycalc.txt文件中。

Answer 2

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.io.FileOutputStream;
import java.io.File;
import javax.swing.JOptionPane;

public class PaycheckCalculator
{

    static final double FEDERAL_TAX = .15, STATE_TAX = .035, SOCIAL_SECURITY = .0575, MEDICARE_MEDICAID = .0275,PENSION = .05;
    static final int HEALTH_INSURANCE = 75;

    public static void main (String[] args) 
    {

        String n = JOptionPane.showInputDialog("enter file name");
        File fileObject = new File(n);
        while (fileObject.exists())
        {
            JOptionPane.showMessageDialog(null,"the file "+fileObject+ "already exists ","Error dialog",JOptionPane.ERROR_MESSAGE);
            JOptionPane.showInputDialog("enter file name again please");
            String g = JOptionPane.showInputDialog("enter file name");
            fileObject = new File(g);
        }
        PrintWriter outFile = null;
        String employeeName = JOptionPane.showInputDialog("Enter your name");
        String inputStr;
        double grossPay, netPay, federal, state, social, medicare, pension;
        int healthInsurance;

        try
        {
          outFile = new PrintWriter(new FileOutputStream(fileObject));  
        }
        catch(FileNotFoundException e)
        {
            System.out.println("this file could not be opened");
            System.exit(0);
        }

          inputStr = JOptionPane.showInputDialog ("Please enter your monthly gross pay: ");

带有文件输出的JOptionPane

2 个答案: