DecimalFormat.format 方法调用：类型不兼容

Question

I wanted to know why there is an error and how to fix it for my java project.

I have to make exactly same out as these:

• What is your annual interest rate as a decimal? (ex: 0.045): .033
• How many years will your mortgage be held? 15
• What amount of the mortgage did you borrow? 300000
• The number 0.033 can be represented as 3.3%
• The mortgage amount is $300,000.00
• The monthly payment in dollars is $2,115.30
• The total payment in over the years in dollars is $380,754.76
• The over-payment is $80,754.76 The over-payment as a percentage of the mortgage is 26.9

And this is what I did on Eclipse;

    double annIntRat;
    int nOY;
    int borrowMor;
    int M;
    double monthPay;
    double mIR;

    Scanner scnr = new Scanner(System.in);

    // Your code should go below this line
    System.out.print("What is your annual interest rate as a decimal? (ex 0.045): ");
    annIntRat = scnr.nextDouble();
    System.out.print("How many years will your mortgage be held? ");
    nOY = scnr.nextInt();
    System.out.print("What amount of the mortgage did you borrow? ");
    borrowMor = scnr.nextInt();     
    DecimalFormat df = new DecimalFormat("0.0");
    System.out.println("\nThe number "+annIntRat+" can be represented as "+df.format((annIntRat)*100)+"%");
    NumberFormat defaultFormat = NumberFormat.getCurrencyInstance();
    M=defaultFormat.format(borrowMor);  //< Here is the error and tells me to change to String.But if I do so, there will be an error down there for monthPay=.....
    System.out.println("The mortgage amount is "+M);
    mIR=(annIntRat)/12;
    monthPay=(mIR * M)/(1-(1/Math.pow(1+mIR,12*nOY)));

Answer 1

It took me a while to see where you highlighted your error, I would recommend being more explicit with where your errors are.

The 'format' method of NumberFormat you are using returns a type of String, which would explain your error.

The following should do the trick, although you can't be certain that a user is to input an integer...take that in mind.

M = Integer.parseInt(defaultFormat.format(borrowMor));

Answer 2

The DecimalFormat.format(long) method is an inherited method from the NumberFormat class — NumberFormat.format(long) . The method returns an instance of String .

So, just use an instance of the String type to store and use the return value of the method:

String borrowMorString = defaultFormat.format(borrowMor);
System.out.println("The mortgage amount is " + borrowMorString);
// …
monthPay = (mIR * borrowMor) / (1 - (1 / Math.pow(1 + mIR, 12 * nOY)));