How to re-prompt a user after invalid input?

February 15, 2022

I have a program that asks the user for 12 months worth of rainfall data. The data being entered can not be below Zero.

How do I re-ask the user to enter valid data while the program stays on the same month?

Affected sections of code:

for(int i = 0; i< month; i++){
            System.out.println("Please enter the rainfall for month " +
                    (i + 1) + ": ");
            thisYear[i] = myScanner.nextDouble();
        }

>Solution :

You could do this with a while loop
For example, let’s say we only want to except values between 1 and 12 we could do

for(int i = 0; i< month; i++){
  System.out.println("Please enter the rainfall for month " +(i + 1) + ": ");
  thisYear[i] = myScanner.nextDouble();
  while((thisYear[i] > 12) || (thisYear[i] < 1)) {//error message
    System.out.println("ERROR Please enter a valid entry");
    System.out.println("");
    System.out.println("Please enter the rainfall for month " +(i + 1) + ": ");
    thisYear[i] = myScanner.nextDouble();
  }
}

This would re prompt the user for an entry if it was outside of that range, you can also add additional parameters using || as logical or