Example a list of contacts
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Example – a list of contacts. See Contact.java at http://www.aber.ac.uk/~dcswww/Dept/Teaching/CourseNotes/current/CS12230/codeExamples/0-simple-examples/Contact.java What if we want the contacts data to persist?. Contact – OO model. UML class diagram Attributes name and phone

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Example – a list of contacts

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Example – a list of contacts

  • See Contact.java at

  • http://www.aber.ac.uk/~dcswww/Dept/Teaching/CourseNotes/current/CS12230/codeExamples/0-simple-examples/Contact.java

  • What if we want the contacts data to persist?


Contact – OO model

  • UML class diagram

  • Attributes name and phone

  • Operation toString()


Contact – ER model

  • Just the attributes

  • No operations

  • Still a UML class diagram


Key-value pairs

  • Name is the key

  • Phone is the value

  • Data model is a kind of persistent hash table


Storage choices

  • Text file

  • Spreadsheet

  • Browser

  • Database

    • Relational

    • Object oriented

    • NoSQL

    • Native XML


Browser

  • HTML5 localStorage

  • localStorage.setItem(key, value)

  • localStorage.getItem(key)

  • For offline use, use appcache

  • Benefits

  • Limitations

  • Example


SQLite

  • Create the SQLite database

  • http://www.sqlite.org/

  • Use a shell tool – a convenient way to create the database in the first place

  • Or write a program


Applications Programming with SQL/CLI

  • Obtain a handle on the database

  • Send SQL queries to the database management system using query functions

  • Process the results of those queries

    • Results are tables and must be transformed into types that the application program can use


Java JDBCimage from http://www.cse.unsw.edu.au/~jas/talks/jdbc/notes.htmlaccessed 15/Oct/2012


Java JDBC

  • Driver manager provides implementations of Connection, Statement and ResultSet

  • Connection acts as database handle

  • Statement enables creation and execution of SQL queries

  • ResultSet maintains a cursor that enables access to current row of data returned by query


SQLite with Java JDBC

  • Suppose you have a database and a jdbc driver

  • In your Java program

    • Initialize the jdbcdriver Class.forName("org.sqlite.JDBC");causes org.sqlite.JDBC to be loaded at runtime

    • Get a connection this.connection= DriverManager.getConnection("jdbc:sqlite:"+dbname);

    • Use the connection to send SQL queries to the database

  • Contacts example


Java Persistence API

  • Alternative to call level interface

  • Work directly with the object oriented data model

  • We’ll revisit this later in the course


Summary

  • First think about

    • Where the data comes from

    • Why the data is stored

    • How it is to be used

  • Then think about

    • Data models

    • Data storage options

    • Applications programming


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