CIS 338: Designing and Developing with VB.NET

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CIS 338 Designing and Developing with VB.NET

• Dr. Ralph D. Westfall
• May, 2011

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Designing a Program

• think first, program later!
• divide and conquer (decompose problem into
  relatively independent parts)
• user interface (1 or more forms)
• unique tasks (done once in program)
• common tasks
• done more than once in your program
• or done in other programs

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Designing a Program - 2

• write out in human language (pseudocode) what
  program and main parts need to do
• sketch out ideas and relationships on paper
• identify sequences
• things that happen first, followed by ...
• identify/work out formulas for calculations
• identify important variables/data items
• inputs, outputs, intermediate results, etc.

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Pseudocode Exercise

• write out pseudocode for a VB application that
• prompts the user for an ID number
• displays the calculated GPA for that student
• assumption
• data comes from a database

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Developing a VB Program

• create user interface items (forms, etc.)
• reevaluate and revise original plan
• write code
• event handlers objectname_Click(
• btnCalculate_Click(
  'button
• common tasks (subroutines, functions)
• comment your code (ONLY where needed)
  'this comment doesn't tell us anything!

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Testing Your Code

• separately develop and test complicated chunks
  of code before implementing
• create "drivers" for unit testing
• look for ways to break the code
• test the other parts of project that interact
  with this subroutine after every (set of)
  changes
• integration testing

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Interface Design Guidelines

• an attractive interface is better than one that
  works just as well but is "ugly"
• users expect similarities with other interfaces
• Exit button location
• efficiency is important
• keep controls close together to reduce amount of
  mouse movement
• Project 1 layout

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Good/Bad User Interface Exercise

• identify some properties of typical VB.NET
  objects/controls e.g.,
• Form, TextBox, Button, ListBox, RadioButton, etc.
• then suggest some
• good values
• bad values
• explain why suggestion is good or bad

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Develop User Interface Examples

• create a VB.NET form with as many bad features as
  possible
• create another form for the same purpose that
  corrects the bad features of the first form

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Pocket PC Interface Example

• identify anything that probably should change in
  the previous design if the application was ported
  over to a Pocket PC
• test your design by developing it as a Smart
  Device application
• or as a Windows application in which the form is
  246 pixels wide by 302 high and the lower part is
  reserved for a keyboard