Programming Basics and Error Handling

Posted on Dec 12, 2023 in Computers

Requirements Phase

Help the customer determine what he/she wants!

  • Sometimes have to help the customer!
  • Document it, including
  • – I/O requirements
  • – Hardware requirements
  • – Speed (throughput) requirements
  • – Software requirements
  • – Functionality desired

For our class

  • Are directions understood and followed?
  • -what the program is supposed to do
  • -input/output requirements
  • -formatting required
  • -correct name for program
  • Is it handed in on the due date?

Design Phase

1.High Level Design

  • Based on Req/Spec Document!
  • Design overall logic
  • Break up project into classes (ie, 
  •      subprojects)  that can be 
  •      individually coded, tested, and 
  •      integrated.   Try to use existing Java classes or make subclasses.

2.Detailed Design

  • Design each individual module or class
  • Should have correct functionality and interfaces, but implementation is “hidden” (does not affect anything else)

For our class

  • Is there overall logic to the program?
  •      (Work out on  paper, flow chart?)
  • Are data structures correct?
  • Is it partitioned into classes correctly?
  • Are global variables used rarely, if at all?
  • Is information and functionality “hidden” – not external but rather localized to classes as much as possible with well-defined assess through methods?
  • Are constants used  so that ranges can  
  •       be easily changed?
  • Are loops used in the right places?
  • Are system functions used when appropriate?

Implementation (Coding)

Based on Detailed Design Documents!

  • Coding…
  • Have code reviews

For our class

  • Are loops called, terminated correctly?
  • Are there any obvious bottlenecks?
Testing Phase

Does it do what the customer wants?  

  • (Validation)
  • Does it do  what it is supposed to?  
  • (Verification)
  • “Black Box” Testing  – 
  •     just input –> output
  • “White Box” Testing – look at internal 
  •      code
  • Unit Testing – for  module individually
  • Integration Testing – do they work 
  •      Together?
  • System Testing – Test everything together in real environment

For our class

  • Does it work with the sample input that 
  •     was handed out?
  • Does it work with additional input?
  • Does it work with “border cases?”
  •   – null input
  •   – large amounts of data
  • – handle errors as specified
  • – handle decision points
Maintenance Phase

Is the program maintainable for the purposes of:

  • –  fixing bugs
  • –  making future enhancements as 
  •     requirements  change
  • –  optimizing
  • –  porting to another platform
  • –  resuming all or part of it in another project

For our class

  • Are there adequate comments?
  • Are the names (for methods, classes,
  •       instances, constants, variables, 
  •        types) meaningful?
  • Is “hard-coding” minimized
  • Is it indented so it is easily understandable?
  • Is white space used to break it up into “sections”?

Syntax error

  • Statement without a ;
  • Spell keyword wrong (main, static,…)
  • Use a variable without declaring it
  • Get a value without initializing it
  • put a double into an int

Logic error

  • Use + when you meant –
  • Expect decimal places from  int/int
  • Set wrong variable
  • Wrong logic for loops, if-elses
  • Many, many possibilities…

Run-time error (“exception”)

  • open a file – but file not there this time
  • divide – but denom. is 0 this time
  • find 6th char in string – but it only has 5 chars this time.
  • Change String to int – but can’t because the String is “45yeui” this time.