Question

我正在为贷款系统创建HomeLoans和CarLoans。需要能够创建用户想要的数量。 switch语句用于菜单。我目前的问题是，当我创建一个家庭娱乐并返回菜单，然后创建另一个，它迫使我发2贷款。我猜是因为我的Homecount ++。然后，当我查看贷款时，它只会记住前两个而不是第一个。如何继续创建贷款并将其添加到数组中，而不会丢失进出switch语句的数据？

public class TestingClasses {

private static Loan getInfo(Scanner scan, char c){

System.out.println("Please enter your Name: ");
String nameOf = scan.next();
System.out.println("Please enter an ID Number: ");
String id_Number = scan.next();
System.out.println("Please enter a Loan Number: ");
String loan_Number = scan.next();
System.out.println("Please enter the amount of the Loan: ");
double loan_Amount = scan.nextDouble();
System.out.println("Please enter your desired Interest Rate: ");
double interest_rate = scan.nextDouble();
while(interest_rate > 100.00){ //Check valid number
    System.out.println("Invalid percentage. Please enter 0.00 - 100.00");
    interest_rate = scan.nextDouble();
}
System.out.println("How long will you like the loan? Please enter 1-30.");
int term = scan.nextInt();
while(term > 30){ // Check for valid number
    System.out.println("Invalid number of years. Please enter 1-30.");
    term = scan.nextInt();
}
System.out.println("Current balance is being set to the Loan amount. \n");
double c_balance = loan_Amount;

if(c == 'H'){

    System.out.println("Please enter an address for the Home: ");
    String address = scan.next();

    return new HomeLoan(nameOf,id_Number,loan_Number,loan_Amount,
    interest_rate,term,c_balance,address);
}
if(c == 'C'){

    System.out.println("Please enter the Make of the car: ");
    String make = scan.next();
    System.out.println("Please enter the Model of the car: ");
    String model = scan.next();
    System.out.println("Please enter the Year of the car: ");
    String year = scan.next();
    return new CarLoan(nameOf,id_Number,loan_Number,loan_Amount,
    interest_rate,term,c_balance,make,model,year);

}
else
    return null;
}

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

    int CarCount=0,HomeCount = 0;
    int j = 0;
            HomeLoan HL[]=null;
    CarLoan CL[]=null;
    Scanner scan = new Scanner(System.in);
    int menuChoice = 0;
    char c;
            HL= new HomeLoan[60];

    String mainMenu = ("Select a choice from the menu: \n" 
            + "1. Create HomeLoan\n" 
            + "2. Create CarLoan\n"
            + "3. Make Payment\n" 
            + "4. Check Balances\n"
            + "5. List of HomeLoans\n" 
            + "6. List of CarLoans\n"
            + "7. Amortization Report\n"
            + "8. Exit");

    System.out.println("Welcome to the Loan system!  \n");

    do{
    System.out.println(mainMenu);
    menuChoice = scan.nextInt();

    while (menuChoice < 1 || menuChoice > 8) {
        System.out.print("\nError! Incorrect choice.\n");
        System.out.println(mainMenu);
        menuChoice = scan.nextInt();
    }


switch (menuChoice) {
    case 1: {

        c = 'H';
         // Add 1 to HomeCount


        for(; j == HomeCount; j++){

            HL[j]=(HomeLoan)getInfo(scan,c);
            System.out.println(HL[j].getHomeLoanNumber());
        }
            HomeCount++;
        break;
        }
    case 2: {

        c = 'C'; 
        CarCount++; // Add 1 to Car Count
        CL = new CarLoan[CarCount];

        for(int j = 0; j < CarCount; j++){ //Loop through loans

            CL[j]=(CarLoan)getInfo(scan,c);
            System.out.println(CL[j].getCarLoanNumber());
        }
        break;
    }
    case 5: {
        for(int k=0; k < HomeCount; k++){
            System.out.println(HL[k]+ "\n");
        }
        break;
    }
    }
    }while(menuChoice != 8); //ending do while loop
    }//end main
}//end class

Answer 1

每次创建新数组时，都会删除以前的数组（好吧，它不会被删除，但是对它的所有引用都会丢失，所以它也可能已被删除）。更好的解决方案是使用ArrayList<Loan>而不是数组，在循环之前创建一次*，然后根据需要简单地将项添加到List。将ArrayList视为可以动态扩展或缩小的数组。

否则，如果你必须使用数组，那么在你声明它时考虑创建一个数组，并在创建它时给它足够的项目，这样你就不会用完空间。 / p>

Answer 2

每次到那里时，您都会在交换机内部将新数组重新分配到HL和CL。因此，它只记得上次迭代的贷款。

切换语句期间的递增计数

2 个答案: