Software Engineering 1 Final

Software Engineering

application of a systematic disciplined quantifiable approach to the development, operation, and maintenance of software

Analysis

Investigation of the requirements

Design

Conceptual solution that fulfills the requirements, rather than its implementation

Object Oriented Analysis

Emphasis on concepts (real world things that pertain to what is required of the software)

Object Oriented Design

emphasis on software objects and how they collaborate to meet requirements

Scrum

(Agile Process) 2-4 week sprints

Agile Process

Breaking projects into little user styories and delivering them in 2 to 4 week sprints

User Story

As a (role) I want (feature) so that I can (accomplish)

Product backlog

Requirements (items in backlog)

Agile Process Stages

Continuous Analysis, Design, Code, Test

Software Design Principle (SDP)

Our plan to build software for customer’s specification

Waterfal

sequential design process

Gantt Diagrams

Boxed waterfall into iterations

Unified Process Stages

Inception, Elaboration, Construction, Transition

Inception Stage of UP

identifying scope and architecture and getting budget (1-2 weeks)

Elaboration Stage of UP

prove we have the right architecture (4-6 weeks)

Construction Stage of UP

build software incrementally requirements as a priority queue (time who knows?)

Transition Stage of UP

Validate system and move to production

Use Case

Textual Story between actors focuses on how system will fulfill a goal (captures requirements)

Requyirement

necessary attribute or constraint of system

SRS

Software Requirements Specification

Virtual Method

any method not private final or static is virtual =meaning it can be overriden by subclasses

Hash Code & Equals

Is a logical comparison rather than a memory location comparison

concept

abstract idea of entity in domain (real world) used during analysis to capture domain knowledge.

class

software construct that defines attributes methods and relationships

Concepts are extracted with

Noun analysis and categorical lists

List (ordered)

has duplicates accessible by index (ArrayList, Linked List)

Set (Unordered)

Collection of unique elements (Hashset, Linked Hashset, Treeset)

Collections are used to

store, retrieve, manipulate, and communicate aggregate data

Op Contract Parts

Name, Cross References, Preconditions, Postconditions

Synchronous Arrow

Caller waits for Callee

Types of Interaction Diagrams

Communication Diagram, Sequence Diagram

Asynchronous Arrow

Sender does not wait

Domain Model

conceptual “analysis” model that reflects real world entities their attributes and relationships

Design Class Model

Concrete implementation-oriented model that shows classes their methods data structures and design patterns etc.

Java primitive types

byte, short, int, long, float, double, char, boolean

Finally block

runs no matter what

Compiler steps

program → asm → result

Interpreter Steps

Program → result

Java compilation steps

java program → compiler →bytecode then to either

1. Java interpreter for Linux

2. For windows

3. For linux

.java -(compilation)→ .class -(interpretation)→ machine code

JRE

Java Runtime Environment

Java Garbage collection

Keeps track of what’s alive, reclaims what isn’t
no explicit deletion and no memory given back to OS.

Wrappers

Short, Integer Double, …

Class based types

String, Date, Calendar

parameters

list of variables in method DECLARATION

arguments

actual values passed into method

Primitives are passed by

value

Objects are passed by

value

GRASP

General Responsibility Assignment Software Patterns

Object Design

1. Identify classes and objects

2. what methods belong where

   1. how these objects interact

Responsibilties:

Doing: doing something itself, initiating action in other objects controlling or coordinating activities in other objects

Knowing: Knowing about private encapsulated data ab out related objects about things it can derive/ calculate

Responsibilities are assigned to classes during

object design

Methods and responsibilities

are not the same, methods implemented to fulfill responsibilities.

Patterns

Principles to guide choices when assigning responsibilities.

A pattern is a named description of a problem with a solution applicable to new contexts.

Controller

who should be responsible for handing an input system event.

Assigns the responsibility

Facade Controller

has few system operations

Use case handler

when there are many system operations among distinct processes or facade controllers would be bloated

Role controller

person like objects instead of delegates

Benefits of controllers

increase potential for reuse
keep external event sources and internal event handlers independent of each other’s type and behavior

Creator

Who should be rsbl for creating a new instc of some class?

Assn class B the rsbl to create an instc of class A if one or more of the following

1. B agg A objs

2. B contains A objs

3. B records ints of A objs

4. B has init data to pass to A when created

Information Expert

What is the general principle of assn rsbls to objs?
Assn a rsbl to the info expert the class that has the info to fulfill the rsbl
Implies many partia experts who will collaborate in the task

Coupling

measure of how strongly one element is connected to has knowledge of, or relies on other elements

High coupling

highly dependent on many others

harder to understand in isolation

harder to reuse with presence of other classes

Cohesion

measure of how strongly related and focused the rsbls of an element are

Low cohesion

Unrelated/Unfocused
hard to understand
hard to reuse
hard to maintain
delicate to change

What kind of coupling and cohesion is desirable?

low coupling & high cohesion

4 kinds of objects (coupling & cohesion)

coupling & cohesion:

low & low: Destructive Decoupling

high & low: Poorly selected boundaries

high & high: God object
low & high: Ideal

Polymorphism

A property of Object Oriented software by which an abstract operation may be performed in different classes (different ways)

Exist when several classes which each implement the operation either have a common superclass or implement an interface that contains the operation

Polymorphism gets its power from

dynamic binding

Dynamic binding

The process of binding a call to a particular method, this is performed dynamically at run-time due to the presence of polymorphism.

Is needed when compiler determines that there are multiple possible methods that could be executed by a call.

Types of java Event handling

1. Event sources (buttons, mouse event)

2. event listener: interfaces to handle events

3. event object: data obj passed to listeners ActionEvent e

Method overloading

The process of redefining a method with the same name with different parameters

3 methods to override when creating a class

1. toString

2. hashCode

3. equals

shortest phase in UP

Inception

SSD

System Sequence Diagram just between actor and black box system

SD

Sequence Diagram, involves what happens on the system side

Can you instantiate an abstract class?

No

Can you implement as many interfaces as you want?

Yes

How to make a button in Java

JButton button = new JButton(“Click”);

What is the top level container in Java Swing called?

JFrame

Coupling

degree of interdependence among modules

Pure Fabrication

When both A and B should have some responsiblity for x, create a fabrication class C for x

SOLID

S - Single Responsibility Principle
O - Open Closed Principle

L - Liskov Substitution Principle
I - Interface Segregation Rule
D - Dependency Inversion Principle

DRY

DONT REPEAT YOURSELF

KISS

Keep it Simple Stupid!

Single Responsibility Principle:

A class should only have a single responsiblity only oen reason to change

Open-Closed Principle

software should be open for extension but closed for modification

Liskov Substitution Principle

Objects should be replaceable wwith subtypes while still being correct

Interface Segregation Rule

Many client specific interfaces are better than one general purpose interface.

Dependency Inversion Principle

One should depend on abstractions not concretions

Indirection

Don’t access directly

Law of Demeter

Don’t talk to strangers (avoid knowing structure of others)

Fault Detection (methods)

Testing, Debugging, Monitoring, Verify/Validate, Unit Testing

Verify vs Validate

Types of Testing

Grey, White Box, Black box testing

Unchecked Exceptions

Log errors caused by programmers runtime error

Checked exception

must be caught or declared (try catch block throws)

Logging levels

Finest, Fine, Config, Info, Warning, Severe

Logger.setLevel(level.warning)

Thread interference

Multiple threads acting on the same data, causes interleaving, sequence of steps overlap