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java - 试图循环到程序的开头

问题描述

如果输入错误，我不知道如何让程序重新启动。

我是 java 新手，不知道如何有效地使用 if 语句或循环。

import java.util.Scanner; 

public class TuitionRates 
{
public static void main(String[] args) 
{
    //variables
    String name = "";
    String studentType = "";
    int creditNumber = 0;
    double totalTF = 0.00;
    double studentACTFee = 4.60;
    double parkingFee = 2.00;
    double tuition = 180.40;
    double capitalFee1 = 0.00;
    double capitalFee2 = 21.00;
    double perCreditR = 187.00;
    double perCreditV = 187.00;
    double perCreditD = 187.00;
    double perCreditM = 208.00;
    double perCreditB = 268.00;
    double perCreditO = 387.25;

    Scanner input = new Scanner(System.in);

    //Asking user for Name
System.out.println("Welcome to the NOVA Tuition and Fees Calculator.");
System.out.println("Please enter your name: ");
name= input.nextLine();

//Ask user to choose option

    System.out.println("Please enter the type of student that your are from 
    the choices below:\n"
            + 
            "R for Virginia Resident\r\n" + 
            "M for Military Contract Out-of-State\r\n" + 
            "V for Military Veterans and Dependents\r\n" + 
            "D for Dual Enrolled\r\n" + 
            "B for Business Contract Students\r\n" + 
            "O for Out of State Students\r\n");

    studentType = input.nextLine();
if (studentType.equalsIgnoreCase("R"))
   {

   System.out.println("Please enter the number of credits that you are 
   taking:");
   creditNumber = input.nextInt();

if (creditNumber <= 18)
{
System.out.println("Tuition and fees report for " + name);          
System.out.println("Tuition: "+ tuition);           
System.out.println( "Capital Fee:  \t"+ capitalFee1);           
System.out.println( "Student Activities Fee: \t "+   studentACTFee);            
System.out.println( "Parking Infrastructure Fee: \t " +  parkingFee);           
System.out.println("Tuition & Fees Per Credit: " +  perCreditR);            
System.out.println("X Number of Credits: " + creditNumber);
totalTF = creditNumber * perCreditR;            
System.out.println("Total Tuition and Fees: \t" +  totalTF);
System.out.println("Bodly NOVA");
}

else {System.out.println("Please re-enter credit Number ");}
}

如果积分数超过 18，我希望我的程序重新启动 if 语句。因此，如果我输入 19，它会说重新输入积分并重新开始 if 语句。

标签： javaloopsif-statement

解决方案

您可以尝试将您的if语句包装在一个do-while循环中：

if (studentType.equalsIgnoreCase("R"))
{
    do{
       System.out.println("Please enter the number of credits that you are taking:");
       creditNumber = input.nextInt();

        if (creditNumber <= 18)
        {
            System.out.println("Tuition and fees report for " + name);          
            System.out.println("Tuition: "+ tuition);           
            System.out.println( "Capital Fee:  \t"+ capitalFee1);           
            System.out.println( "Student Activities Fee: \t "+   studentACTFee);            
            System.out.println( "Parking Infrastructure Fee: \t " +  parkingFee);           
            System.out.println("Tuition & Fees Per Credit: " +  perCreditR);            
            System.out.println("X Number of Credits: " + creditNumber);
            totalTF = creditNumber * perCreditR;            
            System.out.println("Total Tuition and Fees: \t" +  totalTF);
            System.out.println("Bodly NOVA");
        }
        else {System.out.println("Please re-enter credit Number ");}
    }while(creditNumber > 18);
}

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