Key term
CCEA A-Level Software Systems Development CL4
Software and the Development Environment
Topic overviewSystems software and application softwareThe operating system and file managementSource code filesBinary, object and executable filesCompilers, interpreters and the build processXML files and structured dataUtility software and managing files on diskThe integrated development environmentObject oriented development platformsOpen source software and licensing
Defining Data: Types, Variables and Classes
Topic overviewPrimitive types and their storageReference types, objects and nullDeclaring variables, scope and lifetimeType casting and conversionArithmetic operators and expressionsRelational and logical operatorsOperator precedence and evaluation orderObjects as occurrences of a classAbstract, base and inherited classesAttributes and the properties of a classStatic variables in a classInterfaces and class reusability
Program Control Structures
Topic overviewSequence and the order of executionMethods and passing control between themSelection with IF and IF ELSENested IF and multi-way selectionThe switch statementCount-controlled repetition with FORConditional repetition with WHILE and DO WHILENested loops and tracing iterationsBreaking out of loops and avoiding infinite loopsChoosing and evaluating control structures
Objects, Classes and Data Structures
Topic overviewConstructors and creating objectsMethods, parameters and return valuesEncapsulation and access modifiersGetters, setters and validating an object's stateInheritance and the base classOverriding methods and run-time polymorphismOverloading methodsChoosing and organising data structuresStrings and string handlingStatic arrays of simple typesArrays of objects
Exception Handling and Managing Input and Output
Topic overviewWhy errors have to be trappedTypes of error and how an exception is raisedThe try and catch blockCatching more than one kind of exceptionThe finally block and releasing resourcesThrowing exceptions and writing an exception classChecked and unchecked exceptionsReading and validating input from the command lineControlling screen outputText filesBinary filesObject files and serialisation
Testing an Object Oriented Application
Topic overviewWhy an object oriented application must be testedChoosing test data: normal, boundary and erroneousWriting a test plan for a classTesting a class method by methodTesting constructors and object stateTesting inheritance and overridden methodsTesting error handling pathsDry runs and trace tablesTest harnesses, drivers and stubsRecording and interpreting test resultsEvaluating a test plan and re-testing
Graphical User Interface Objects and Events
Topic overviewGraphical user interfaces and console programsForms and their common propertiesLabels, text boxes and text areasButtons, check boxes and radio buttonsLists, combo boxes and other selection controlsProperties, methods and events of a GUI objectContainers, panels and laying out a formThe event loop and the event queueEvent handlers and registering a listenerThe event object and reading it inside a handlerButton, mouse and keyboard triggers
Multiple Forms and Linking to Files
Topic overviewWhy an application needs more than one formCreating, showing, hiding and closing a formModal and modeless formsPassing data between formsMenus, menu items and shortcutsToolbars and navigation buttonsDesigning navigation for a multi form applicationReading and writing text filesBinary files and streamsObject serialisation and object filesChoosing between text, binary and object files
Designing, Testing and Evaluating an Event Driven Application
Topic overviewStoryboards and what they showBuilding a storyboard from user requirementsPrototyping and refining a designError trapping in an event driven applicationUsing try and catch inside an event handlerValidating what a user types into a controlDesigning a test strategy for an event driven applicationTest plans and choosing test dataTesting the paths a user takes through an interfaceDocumenting and interpreting test resultsEvaluating an application against its requirementsEvaluating features, functionality and usability
Reasons for Systems Development and Systems Methodologies
Topic overviewWhy organisations initiate systems developmentAnalysis and design principles for business solutionsRoles in development and the place of the userThe purpose of a methodology and how methodologies evolvedThe waterfall modelIterative, incremental and spiral developmentRapid application developmentThe dynamic systems development methodScrumExtreme programmingPrototyping in the development processUML modelling and simple diagrams
Managing Projects
Topic overviewThe purpose of project managementProject management concepts and the project life cycleRoles and responsibilities in project managementResources needed to develop a projectEstimating effort, duration and costGantt charts and the scheduleMilestones and checkpointsNetwork diagrams and PERTFinding the critical pathFloat and how it is usedMonitoring and controlling progressManaging risk and change
Testing Strategies
Topic overviewWhy testing matters throughout the development cycleTesting at the design stageProgram and unit testingIntegration testingSystem testingWhite box testingBlack box testingNormal, boundary and erroneous test dataUser acceptance, alpha and beta testingThe personnel involved in testingWhat a test plan containsBuilding a test plan for a scenario
Database Concepts and Entity Relationship Modelling
Topic overviewWhat a database is and why one is usedDatabase terminology: fields, records and keysThe relational modelThe hierarchical modelThe network modelEntities and attributes in an ER modelRelationships and their degreeBuilding an ER model for a problemFrom ER model to a working designComparing the three database models
Normalisation and Structured Query Language
Topic overviewWhy data is normalisedUn-normalised data and repeating groupsFirst normal formSecond normal formThird normal formWorking a full normalisation throughThe advantages and limits of normalisationThe principles of SQLSQL commands for defining and changing dataSQL statements for retrieving dataJoining tables and grouping results
Project Management and the Systems Approach in Practice
Topic overviewBreaking a development into tasks and deliverablesEstimating durations, effort and dependenciesDocumenting the plan as a Gantt chartWorking out the critical path and floatMilestones, reviews and user sign-off pointsPlanning people, resources and skillsBuilding a plan capable of reflecting changeRecording progress against the planUpdating the plan to reflect slippageRecording change requests and versions of the planEvaluating different approaches to a business problemSelecting and justifying a specific approach
Defining Requirements and Documenting the Design
Topic overviewEliciting requirements from the userWriting functional requirementsWriting non-functional requirementsSpecifying the software and hardware the solution needsProducing and agreeing the user requirements specificationDesigning the data model and the tablesDesigning the inputs, the screens and the navigationDesigning the outputs and the reportsDocumenting the processes and the logic of the solutionTesting the design against the desired user outcomesPresenting the design and the solution using appropriate media
Building a Desktop Solution with a Database
Topic overviewApplying relational techniques to a real solutionChoosing the database and the development toolConnecting the application to the databaseData adaptorsData setsData commands and parameterised queriesBinding the database to the interfaceMultiple forms and navigationSaving changes and protecting the dataTesting and documenting the built solution
Testing and Evaluating the Solution
Topic overviewPlanning the testing of the finished solutionChoosing test data: normal, boundary and erroneousTesting validation and error handlingTesting the database and its queriesTesting the user interface and the navigationTesting the whole solution and testing with the userDocumenting test outcomes as evidenceDiagnosing failures and retestingEvaluating the test proceduresEvaluating the solution against the user requirementsEvaluating delivery against the project planEvaluating your own performance on the development
Exception Handling and Managing Input and Output
The finally block and releasing resources
- 3 things to know
- AS Unit 1
Overview
Finally block and resource leak.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why might closing a file itself need to be inside a try block?
Key term
What is a finally block normally used for?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is a finally block?
Model answer
A finally block is written after the catch blocks and its statements run whether or not an exception was thrown, so it holds work that must happen either way.
- 2
What is a finally block normally used for?
Model answer
A finally block normally releases resources, closing an open file, a database connection or a network socket, so nothing is left held after the method finishes.
- 3
Does a finally block run when no exception occurs?
Model answer
The finally block runs after the try block has completed normally, just as it runs after a catch block has dealt with a fault.
- 4
Does a finally block run when the exception is not caught at all?
Model answer
The finally block still runs as the method is abandoned, so the clean-up happens before the exception travels out to the calling method.
- 5
Does a finally block run when the try block executes a return?
Model answer
The finally block runs before the method actually returns, so a value on its way back to the caller does not allow the clean-up to be skipped.
- 6
A program runs try { System.out.println("1"); throw new Exception(); } catch (Exception e) { System.out.println("2"); } finally { System.out.println("3"); } and then System.out.println("4");. What is printed?
Model answer
The try prints 1 and then throws, so the handler prints 2, the finally prints 3 because it always runs, and execution continues to print 4, giving 1, 2, 3 and 4.
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