Answer:
- Will the instance variable
balancehold its value permanently?- Yes —
balanceis part of the state of the object and holds its value as long as the object exists.
- Yes —
- Will the parameter
amounthold its value permanently?- No —
amountis used only to pass in a value into the method. It is not permanent.
- No —
Formal and Actual Parameters
An identifier is a name used for a class, a variable, a method, or a parameter. The following definitions are useful:
- formal parameter — the identifier used in a method to stand for the
value that is passed into the method by a caller.
- For example,
amountis a formal parameter ofprocessDeposit
- For example,
- actual parameter — the actual value that
is passed into the method by a caller.
- For example, the
200used whenprocessDepositis called is an actual parameter.
- For example, the
When a method is called, the formal parameter is temporarily "bound" to the actual parameter. The method uses the formal parameter to stand for the actual value that the caller wants to be used.
For example, here
the processDeposit method
uses the formal parameter amount
to stand for the actual value
used in the procedure call:
balance = balance + amount ;
Note: formal parameters are bound to an actual value only as long as their method is active. When a method returns to its caller, the formal parameters no longer contain any values. They cannot be used to store the state of an object.
QUESTION 3:
What is used to store the state of an object?