Writing Data to a Sequential Data File - Java Programming: Comprehensive Concepts and Techniques - page 491

Five message and dialog boxes summarized in Table 8-2 will be needed. The
solution should use one of the JOptionPane show() methods to specify the type
of box that displays with the appropriate title, prompt, icon, and buttons.

Table 8-2 BillPayer Message and Dialog Boxes
TYPE OF BOX TITLE PROMPT ICON BUTTONS

1 MessageDialog Error The UIManager could not set the Look Information OK

and Feel for this application.

2 MessageDialog Error The program could not create a storage Information OK

location. Please check the disk drive and
then run the program again.

3 ConfirmDialog File Are you sure you want to exit Question YES/NO

Submission and submit the file?

4 MessageDialog Submission The payment information has been saved. Information OK

Successful

5 MessageDialog Data Entry You must complete all fields. Warning OK

Error

Box 1 displays if the program generates an
exception because it is unable to access the chosen
Look and Feel. Box 2 displays if the program gen-
erates an exception because the disk is full or the
program cannot access the secondary storage
device. Box 3 displays when the user clicks the
Close button on the title bar. Box 4 displays when
the user clicks the Submit button. Finally, Box 5
displays if the user clicks the Submit button and
one or more of the text boxes are empty.

Create BillPayer application

Construct components

Construct window and set attributes

Add components to window

Try to open output file
If storage is inaccessible

Notify user

Exit program

PROGRAM DESIGN Once the interface is
designed, the next step is to design the logic to
solve the problem and create the desired results.
Figure 8-4 shows the pseudocode that represents
the logic of the program.
After the interface components are con-
structed and added to the appropriate containers,
the program should open the sequential file and
display the interface. The user then has three pos-
sible choices: enter data into the text fields, click
the Submit button, or click the Close button on
the title bar. If the user clicks the Submit button
with a field blank, the program should display an
error message; otherwise, the data should be writ-
ten to the sequential file, and a submission mes-
sage should display. In order to maximize the
speed of data entry, users will not be required to
enter the payment amount using a certain format.

Display interface

When Close button is clicked

Display confirmation display box

If yes

Close program

Else

Return to interface

When Submit button is clicked

If any field is empty
error message

Display

Return to interface

Else

Write data to disk

Display submission message

Clear fields

Return to interface

End BillPayer application

FIGURE 8-4