Creating Menus and Button Arrays Using the Abstract Windows Toolkit - Java Programming: Comprehensive Concepts and Techniques - page 381

Program Development
The program development cycle for the Calculator application consists of tasks
that correspond to the six development cycle phases, as shown in Table 6-1.

Table 6-1 Calculator Application Development Tasks
DEVELOPMENT PHASE TASK(S)

1 Analyze the requirements Analyze the Calculator problem.

2 Design the solution Design the user interface for the application

and the menu, including placement of the
components. Design the logic to make the
calculator and its menu work.

3 Validate the design Confirm with the user that the design solves the

problem in a satisfactory manner.

4 Implement the design Translate the design into code. Include internal

documentation (comments and remarks) within
the code that explains the purpose of the code
statements.

5 Test the solution Test the program by trying each operator button

and each menu option. Find and correct any
errors (debug) until it is error-free.

6 Document the solution Print copies of the application code.

Analysis and Design

Figure 6-2 on the next page shows the requirements document that initiates
the development cycle for the Calculator application. The requirements docu-
ment specifies the reason for the request and describes the features required in
the Calculator application.

PROBLEM ANALYSIS A software engineering company wants a Calculator
application written in Java with a small set of menu options, including com-
mands to cut and paste. In order to make the calculator as user-friendly as
possible, it should display in a standard window with Minimize, Maximize, and
Close buttons. In addition, the user should be able to resize the window by drag-
ging its border. As shown in Figure 6-1, the calculator should have ten numeric
buttons (numbered 0-9), four operator buttons, a decimal point, and an equal
button. When the user clicks a numeric button, the digits should display at the
top of the window in a small area similar to an LCD screen on a handheld calcu-
lator. When the user clicks an operator button, such as addition (+) or subtrac-
tion (-), the program should clear the display and allow for the next operand.
The program will need to remember the operands and the operators as the user
enters them in order to perform the calculation correctly. When the user clicks
the equal button, the calculator should display the answer at the top of the
window.