Account class

The source code for the account class is illustrated below. The class has two factory methods:

•	addAccount adds 1 to the value of number-of-accounts, and

•	removeAccount subtracts 1 from the value of number-of-accounts.

The account class also has six instance methods:

•	newAccount creates a new instance of an account object,

•	displayUI displays the value of the account balance or performs another function based on a user's request,

•	balance retrieves the balance of the account,

•	deposit adds an amount to the current balance of the account,

•	withdraw subtracts an amount from the current balance of the account,

•	initializeAccount moves initial values into the instance data.

CLASS-ID. Account. ENVIRONMENT DIVISION. CONFIGURATION SECTION. REPOSITORY. IDENTIFICATION DIVISION. FACTORY. DATA DIVISION. WORKING-STORAGE SECTION. 01  number-of-accounts     PIC 9(5) VALUE ZERO. PROCEDURE DIVISION.   IDENTIFICATION DIVISION. METHOD-ID. addAccount as "addAccount". PROCEDURE DIVISION. method-start.     ADD 1 TO number-of-accounts. END METHOD.   IDENTIFICATION DIVISION. METHOD-ID. removeAccount as "removeAccount". PROCEDURE DIVISION. main-entry.     SUBTRACT 1 FROM number-of-accounts. END METHOD. END FACTORY.   IDENTIFICATION DIVISION. OBJECT. DATA DIVISION. WORKING-STORAGE SECTION. 01  account-balance        PIC S9(9)V99. 01  account-number         PIC X(9). 01  the-date               PIC 9(8). PROCEDURE DIVISION.   IDENTIFICATION DIVISION. METHOD-ID. newAccount as "new". DATA DIVISION. PROCEDURE DIVISION. begin-here.     INVOKE SELF "initializeAccount" USING BY CONTENT number-of-accounts. END METHOD.

IDENTIFICATION DIVISION. METHOD-ID. displayUI as "displayUI". DATA DIVISION. WORKING-STORAGE SECTION. 01  in-data.     03 action-type         PIC X.     03 in-amount           PIC S9(9)V99.     03 in-wrk              PIC X(12). PROCEDURE DIVISION. method-start.     DISPLAY "Enter D for Deposit, B for Balance or W for Withdrawal"     ACCEPT in-data     EVALUATE action-type     WHEN "D"          PERFORM get-amount          INVOKE SELF "deposit" USING in-amount     WHEN "W"          PERFORM get-amount          INVOKE SELF "withdraw" USING in-amount     WHEN "B"          INVOKE SELF "balance"     WHEN OTHER          DISPLAY "Enter valid transaction type."          GOBACK     END-EVALUATE     GOBACK     . get-amount.     DISPLAY "Enter amount 9(9).99"     ACCEPT in-wrk     COMPUTE in-amount = FUNCTION NUMVAL (in-wrk)     . END METHOD.   IDENTIFICATION DIVISION. METHOD-ID. balance as "balance". DATA DIVISION. WORKING-STORAGE SECTION. 01  display-balance        PIC $ZZZ,ZZZ,ZZ9.99. PROCEDURE DIVISION. disp-balance.     MOVE account-balance to display-balance     DISPLAY "Your Account Balance is:" display-balance END METHOD.   IDENTIFICATION DIVISION. METHOD-ID. deposit as "deposit". DATA DIVISION. LINKAGE SECTION. 01  in-deposit             PIC S9(9)V99. PROCEDURE DIVISION USING in-deposit. make-deposit.     ADD in-deposit TO account-balance END METHOD.

IDENTIFICATION DIVISION. METHOD-ID. withdraw as "withdraw". DATA DIVISION. LINKAGE SECTION. 01  in-withdraw            PIC S9(9)V99. PROCEDURE DIVISION USING in-withdraw. withdraw-start.     IF account-balance >= in-withdraw        SUBTRACT in-withdraw FROM account-balance     ELSE        DISPLAY "Your Balance is Inadequate"     END-IF END METHOD.   IDENTIFICATION DIVISION. METHOD-ID. initializeAccount as "initializeAccount". DATA DIVISION. LINKAGE SECTION. 01  new-account-number     PIC 9(5). PROCEDURE DIVISION USING new-account-number. Begin-initialization.     MOVE ZERO TO account-balance     MOVE new-account-number TO account-number     ACCEPT the-date FROM CENTURY-DATE END METHOD. END OBJECT.

The following statements from the above code

INVOKE SELF "initializeAccount" USING BY CONTENT number-of-accounts INVOKE SELF "deposit" USING in-amount INVOKE SELF "withdraw" USING in-amount INVOKE SELF "balance"

could also be written as

SELF:>initializeAccount (number-of-accounts) SELF:>deposit (in-amount) SELF:>withdraw (in-amount) SELF:>balance ()

The main advantages in using the object:>method syntax instead of INVOKE are:

•	the code is more similar to Java code, so it’s easier to write down a cobol program that uses objects by converting an existing Java sample.

•	more statements can appear in the same exception block. E.g., the following code

INVOKE myObj "method1"    ON EXCEPTION      DISPLAY MESSAGE exception-object:>getMessage() END-INVOKE. INVOKE myObj "method2"    ON EXCEPTION      DISPLAY MESSAGE exception-object:>getMessage() END-INVOKE.

can be written as

TRY    myObj:>method1();    myObj:>method2(); CATCH EXCETPION    DISPLAY MESSAGE exception-object:>getMessage() END-TRY.

•

Nested method invocation can be used. E.g., consider having an object named objParent, that provides a method called getChild. The getChild method returns and instance of objChild object, that has a method called doSomething. In order to use the doSomething method with INVOKE statement, two steps are required:

INVOKE objParent "getChild" GIVING objChild. INVOKE objChild "doSomething".

With the object:>method syntax, instead, the objective can be achieved with one single statement:

objParent:>getChild:>doSomething().

Note - object:>method could be considered as a parameter of a previous COBOL statement if

•	the previous COBOL statement supports multiple parameters (e.g. MOVE or DISPLAY)

•	the previous COBOL statement isn’t closed

If it’s not possible to close the previous statement with a dot, use two semicolons.

For example, the following code is not accurate and leads to compiler errors and unwanted runtime behaviors:

if test-var = 1    move 0 to test-var    myObj:>myMethod1() end-if display test-var myObj:>myMethod2()

myObj:>myMethod1 would be considered as a second parameter of the previous MOVE while the result of myObj:>myMethod2 would be displayed along with test-var.

The above code can be corrected as follows:

if test-var = 1    move 0 to test-var;;    myObj:>myMethod1() end-if display test-var. myObj:>myMethod2()