XML for Android Developers. partially adapted from XML Tutorial by W3Schools

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1 XML for Android Developers partially adapted from XML Tutorial by W3Schools

2 Markup Language A system for annotating a text document in way that is syntactically distinguishble from the content. Motivated by the old editorial practice of marking up paper documents with colored pencil. HTML LaTeX Wikitext MathML News, weather, music, scientific measurements,...

3 HTML <!DOCTYPE html> <html> <head> <title>fears</title> </head> <body> i am scared of: <ol> <li>sharks</li> <li>tornados</li> <li>sharp glass</li> <ol> i avoid these things. </body> </html>

4 EXtensible Markup Language Tags and document structure defined by author. Human-readable, machine independent, plain text. Intended for storage and transmission of data. XHTML MathML CML (Chemical Markup Language) SVG (Scalable Vector Graphics) Java FXML Android UI layouts

5 EXtensible Markup Language <command> <priority>high</priority> <from> <rank>capt</rank> <name>jones</name> </from> <to> <rank>sgt</rank> <name>smith</name> </to> <subject>secret Battle Plan</subject> <body>attack AT DAWN</body> </command>

6 XML Tree Structure command priority from to subject body High rank name rank name Secret Battle Plan ATTACK AT DAWN Capt Jones Sgt Smith

7 Elements vs. Attributes <command> <date>december 24, 2017</date> <priority>high</priority> <from>jones</from> <to>smith</to> <body>attack AT DAWN</body> </command>

8 Elements vs. Attributes <command> <date>december 24, 2017</date> <priority>high</priority> <from>jones</from> <to>smith</to> <body>attack AT DAWN</body> </command> <command date= December 24, 2017 > <priority>high</priority> <from>jones</from> <to>smith</to> <body>attack AT DAWN</body> </command>

9 Elements vs. Attributes <command date= December 24, 2017 > <priority>high</priority> <from>jones</from> <to>smith</to> <msg>attack at dawn.</msg> </command> <command> <date> <month>december</month> <day>24</day> <year>2017</year> </date> <priority>high</priority> <from>jones</from> <to>smith</to> <msg>attack at dawn.</msg> </command>

10 Elements vs. Attributes <command date= December 24, 2017, priority= high, from= Jones, to= Smith, msg= Attack at dawn. > </command> Attributes cannot contain multiple values. Attributes do not have a tree structure. Attributes are not easily expandable. Use attributes for meta-data (e.g., ID numbers)...?

11 XML Syntax Optional prolog <?xml version="1.0" encoding="utf-8"?> Tags are case sensitive. Every element has a closing tag. Elements can contain text, attributes, and/or other elements. One root element (no parent, ancestor of all other elements). Attribute values must be quoted. Elements must be properly nested.

12 XML Syntax Five predefined entity references < > & ' &quote;  Whitespace is preserved (cf. HTML) <subject>secret Battle Plan</subject> <subject>secret Battle Plan</subject>

13 FXML BorderPane border = new BorderPane(); Label text = new Label("Test of Obedience"); border.setcenter(text); Button btn = new Button("CLICK ME NOW"); border.setbottom(btn);

14 FXML BorderPane border = new BorderPane(); Label text = new Label("Test of Obedience"); border.setcenter(text); Button btn = new Button("CLICK ME NOW"); border.setbottom(btn); <BorderPane> <center> <Label text="test of Obedience"/> </center> <bottom> <Button text="click ME NOW"/> </bottom> </BorderPane>

15 layout.xml <LinearLayout xmlns:android = " android:layout_width = "fill_parent android:layout_height = "fill_parent > <CheckBox android:id = "@+id/checkbox android:layout_width = "wrap_content android:layout_height = "wrap_content android:text = "Yes"/> </LinearLayout> <element xmlns:name="url"> namespace prefix namespace identifier

16 Document Type Declarations Well formed: correct XML syntax Valid: well formed and complies with DTD <?xml version= 1.0 encoding= UTF-8?> <!DOCTYPE command SYSTEM Command.dtd > <command> </command>

17 Document Type Declarations Well formed: correct XML syntax Valid: well formed and complies with DTD <?xml version= 1.0 encoding= UTF-8?> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" " <html> </html> <!DOCTYPE [name] PUBLIC [public identifier] [system identifier]

18 DTDs vs. Schema <!DOCTYPE note [ <!ELEMENT note (to,from,heading,body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)> ]> <xs:element name="note"> <xs:complextype> <xs:sequence> <xs:element name="to" type="xs:string"/> <xs:element name="from" type="xs:string"/> <xs:element name="heading" type="xs:string"/> <xs:element name="body" type="xs:string"/> </xs:sequence> </xs:complextype> </xs:element>

markup language carry data define your own tags self-descriptive W3C Recommendation

markup language carry data define your own tags self-descriptive W3C Recommendation XML intro What is XML? XML stands for EXtensible Markup Language XML is a markup language much like HTML XML was designed to carry data, not to display data XML tags are not predefined. You must define