java - 带循环的输入和输出

Question

我需要编写一个程序，从输入文件中获取 3 个学生信息。根据扫描的学分确定他们是全日制还是非全日制学生后计算学费，然后将他们的所有信息输出到输出文件。到目前为止，我非常有信心大多数代码都能正常工作，但我遇到了问题。

我们的类(class)刚刚复习了有关循环的 Material ，我需要确保代码使用这样的 Material 。到目前为止，我使用 while 循环来扫描整个文件直到结束。虽然它确实获得了所需的学生信息。它只打印最后一个，所以显然只得到 1 个总数，然后用下一部分覆盖相同的一个。这是代码。

我或多或少只需要输入和可能输出方面的帮助。

至于输入文件，如下

Dom Pilorusso
1037 Waterford Court
Canonsburg PA 15317
C937493021
15

Dan Madeupname
106 Cidar Lane
McMurray PA 15317
C927012312
11

Steve Arnold
281 Maple Drive
Canonsburg PA 15317
C482716209
9

<小时/>

public class Program4 {

// Sets the prices for full time and part time students.

static final double TUITION_PER_CREDIT = 276.00;
static final double FEE_PER_CREDIT     = 15.00;
static final double SERVICE_PER_CREDIT = 7.09;
static final double FULL_TIME_TUITION  = 3311.00;
static final double FULL_TIME_FEE      = 184.00;
static final double FULL_TIME_SERVICE  = 85.00;


public static void main(String[] args) throws FileNotFoundException
{
    int i                       ;
    String firstName      =null ;
    String lastName       =null ;
    String accountNumber  =null ;
    double creditsTaken = 0     ;
    String address1             ;
    String address, address2, address3, address4, address5, address6;      
    String fileName             ;
    double tuition      = 0     ;
    double fees         = 0     ;
    double total        = 0     ;
    String formatFees           ;
    String formatTotal          ;
    String formatTuition        ;

            //create a scanner object named inFile and assign it the file input.dat
            fileName = JOptionPane.showInputDialog("Please enter the input file name. ");

            Scanner inFile = new Scanner (new FileReader(fileName));

            //create a PrintWriter object named outFile associated with the file output.dat
            PrintWriter outFile = new PrintWriter ("tuitionAndFees.dat");

            //Intended to loop the input until the end of the file.

    while (inFile.hasNext())
    {   firstName     = inFile.next();
        lastName      = inFile.next();
        address       = inFile.next();
        address2      = inFile.next();
        address3      = inFile.next();
        address4      = inFile.next();
        address5      = inFile.next();
        address6      = inFile.next();
        accountNumber = inFile.next();
        creditsTaken  = inFile.nextDouble();
    }  

    //If Else statement to determine if the student is a part time or full time student, and then calculates their bill.
        if(creditsTaken < 12)
        {   tuition = TUITION_PER_CREDIT * creditsTaken;
            fees    =(FEE_PER_CREDIT + SERVICE_PER_CREDIT) * creditsTaken;
            total   = tuition + fees;

        }

        else
        {
            tuition = FULL_TIME_TUITION;
            fees    = FULL_TIME_FEE +  FULL_TIME_SERVICE;
            total   = tuition + fees;
        }
       formatTotal   = String.format("%.2f", total);
       formatFees    = String.format("%.2f", fees);
       formatTuition = String.format("%.2f", tuition);

       //Output to file all info, needs fixed.
       outFile.println("Tuition Billing Report ");
       outFile.printf("CWID\t\t"+ "Name\t\t"+ "Credits\t\t"+ "Tuition\t\t"+ "Fees\t\t"+ "Total%n");
       outFile.printf(accountNumber + "\t"+ firstName + " "+ lastName + "\t"+ creditsTaken + "\t\t" + formatTuition + "\t\t" + formatFees + "\t\t" +formatTotal);

       inFile.close();
       outFile.close();

       JOptionPane.showMessageDialog(null, "The program was saved in tuitionAndFees.dat");
    } 
  }

Answer 1

您只创建了每个变量之一，并且在正确浏览文件的同时，您不断地将值分配给变量并覆盖以前的值。

您有 3 个选择:

1 - 为每个变量创建一系列数组并在期间分配值(这是有点糟糕的结构化编程)

2 - 您创建一个类，用所有变量表示您的学生实体，并在创建实例并将每个实例分配给数组位置(学生数组)的同时进行

3 - 你读取每一行并进行你想要的处理(有时这会让事情变得有点困难，因为你可能必须有很多操作系统累加器和辅助变量)

我会选择选项 2。