Suppose you want to change the implementation of the class DigitalTime given in Displays 12.1 and 12.2. Specifically, you want to change the way the time is recorded. Instead of using the two private variables hour and minute, you want to use a single (private) int variable, which will be called minutes. In this new implementation the private variable minutes will record the time as the number of minutes since the time 0:00 (that is, since midnight). So 1:30 is recorded as 90 minutes, since it is 90 minutes past midnight. Describe how you need to change the interface and implementation files shown in Displays 12.1 and 12.2. You need not write out the files in their entirety; just indicate what items you need to change and how, in a very general way, you would change them.

Display 12.2