Calling another method in the class from within the body of a method Im wri

Question

Hello out there.
I have a question. I keep getting an error that reads as follows:
1 error found:
File: /Users/matthieubell/Academia/University of Waterloo/CS 125/L06/CreditCard.java [line: 80]
Error: double cannot be dereferenced
I think it is occuring because I am trying to call a method on an instance variable, which is not an object. But how do call a method I have already written, on another method I am writing in the general sense. I could make a particular object, but Im not shure that would get me the same result. I want to be able to call the method calcMinPayment on the instance variable currentBalance to wirte the method makePayment.
I have a class CreditCard
with the instance variables "private double currentBalance = 0; "
public double calcMinPayment()
// Add code here
double minimumPayment;
if (currentBalance < 50)
minimumPayment = currentBalance/10;
else
minimumPayment = 50;
return minimumPayment; // Replace this statement
* This method will decrease the current balance on the credit card if
* this payment meets or exceeds the minimum payment amount.
* pre: paymentAmt > 0
* post: The current balance should be decreased by paymentAmt if
* paymentAmt >= the minimum payment amount. Otherwise, the payment
* will not be recorded and an appropriate error message should be
* displayed.
public void makePayment(double paymentAmt)
// Add code here
double minimumPaymentAmount;
minimumPaymentAmount = currentBalance.calcMinPayment();
if (paymentAmt < minimumPaymentAmount)
System.out.println("Sorry, but your payment must exceed the minimum payment amount.");
System.out.println("This payment has not been recorded, please try again.");
else
this.currentBalance = currentBalance - paymentAmt;
thanks for youre help
-Matthieu

Answer 1

'calcMinPayment' takes no arguments, uses a member variable (currentBalance) to compute a local variable 'minimumPayment' which it returns, ie, sends back to the caller. So you can call 'calcMinPayment' at any time.
minimumPaymentAmount = calcMinPayment();