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In these examples we will define two classes of objects, bank customers
(class Customer) and bank accounts (class Account).
We will slowly build these classes by adding different components.
At each step , the name of the classes will increase by 1,
starting with Account1 and Customer1.
Starting with the third step, you can run a banking application
which demonstrated the new features in that step.
- Instance variables specify the properties of the objects.
See the variables in
Customer1.java
and
Account1.java
- Instance methods specify the behaviour of the objects.
See the methods in
Customer2.java
and
Account2.java
- Constructor methods are used to specify how the class is
instantiated, i.e. how new objects of that class are created.
Constructor methods have the same name as the class.
See
Customer3.java
,
Account3.java
and
Banking3.java.
In this example, one customer is created with one account.
Then the account is manipulated.
- However, one can create multiple instances of the same class.
See
Customer4.java
,
Account4.java
and
Banking4.java.
In this example, each object responds to requests for information
send via the WhoAmI method.
- Class variables are used to keep information that is
meant to be shared by all instances of the class.
See
Account5.java
and
Banking5.java.
There is no change to the Customer class in this example, so
Customer4.java
is used.
In this example,
the class variable accountID has been added to the Account class
to generate different account IDs to each account.
- Class variables can also be public, when information belongs
to a class but is meant to be easily shared outside.
In
Account6.java
and
Banking6.java.
the credit ratings are defined in the
Customer6.java
class because they belong to customers.
- Classes can have multiple constructors, all with the same names,
but with different parameter structures.
In
Customer7.java
the class Customer7 has multiple constructors to deal with various
situations.
This is demonstrated in the
Banking7.java.
program.
When a method has multiple definitions, this is called
method overloading.
- Methods can also be associated with entire classes instead of
with objects in the class. These are called class methods.
In the following examples, a new class method to send messages
to all objects in one class is added.
This page is maintained by Sophie Quigley, e-mail:
quigley@torontomu.ca
Last modified
Friday, 26-Sep-2003 00:09:15 EDT