Writing Classes - Java Software Solutions: Foundations of Program Design - page 180

transactions on the account, adjusting the balance based on the parameters. There
is also an addInterest method that updates the balance by adding in the interest
earned. These methods represent valid ways to change the balance, so a classic
mutator such as setBalance is not provided.
The status of the three Account objects just after they were created in the
Transactions program could be depicted as follows:

acctNumber 72354

balance 102.56

acct1

name

"Ted Murphy"

acctNumber 69713

balance 40.00

acct2

name

"Jane Smith"

acctNumber 93757

balance 759.32

acct3

name

"Edward Demsey"

The various methods that update the balance of the account could be more
rigorously designed. Checks should be made to ensure that the parameter values
are valid, such as preventing the withdrawal of a negative amount (which would
essentially be a deposit). This processing is discussed in the next chapter.

SELF-REVIEW QUESTIONS (see answers in Appendix N)
SR 4.16 Why is a method invoked through (or on) a particular object? What is
the exception to that rule?
SR 4.17 What does it mean for a method to return a value?
SR 4.18 What does the return statement do?
SR 4.19 Is a return statement required?