Object-Oriented Programming with Java Lecture Notes

24 January 2008 • Object-Oriented Programming

Outline

• OOP vs. data abstraction.

• Effective data abstraction.

• OOP facilities.

• Limits.

Paradigms

• A programming technique.

• Support vs. enabling.

• Support is pervasive.

Support Quality

• Clean, elegant integration in the language.

• Integration with other functions.

• Few or no corner cases or exceptions.

• You pay for only what you use.

Procedural Programming

• Programs are procedures manipulating data.

• FORTRAN, Algol, Pascal.

• Example: is a tic-tac-toe board winning?

  bool isWinning(const ttt-board & b) const;
  

Data Handling

• Procedures need data.

• What is data.

• Data shape affects how a procedure works.

• A tic-tac-toe board is a vector or a matrix.

Data Hiding

• The procedure data-shape dependence.

• Minimize the dependence.

• Minimize the data “surface area.”

• Present only and exactly the necessary functions.

Example

• What's necessary about a tic-tac-toe board?

• The contents of individual squares.

• Everything else can be derived.

• Important to program design.

Data Abstraction

• Data hiding decouples procedures and data.

• Decoupled data is independent.

• Language began to support data abstraction.

• This made data and procedures equal.

Consequences

• Minimal independent data off-loads work.

• Off-loaded work leads to redundancy.

• A multiplicity of data leads to complexity.

Object-Oriented Programming

• Programming is data-objects interacting.

• A program is a model of the problem.

• Programming is modelling.

• And also analysis and design.

References

• What is “Object-Oriented Programming”? by Bjarne Stroustrup at AT&T Bell Labs, 1991.