Financial Engineering Project Course

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Financial Engineering Project Course
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Lecture 5

• Validation against a DTD
• More Java Details
• Validating the swap agreement using Suns
• JAXP API

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Checking the Structure of an XML document with an
XML parser
Document
Valid XML
XML Rules Checker (Parser)
Structure Rules (DTD)
Invalid XML
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Operation of a Tree-based Parser
XML DTD
Document Tree
Tree-Based Parser
Application Logic
Valid
XML Document
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The Agreement.xml file
lt?xml version"1.0" encoding"UTF-8"?gt lt!DOCTYPE
FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"gt ltFixed
FloatSwapgt ltNotionalgt100lt/Notionalgt
ltFixed_Rategt5lt/Fixed_Rategt ltNumYearsgt3lt/NumYear
sgt ltNumPaymentsgt6lt/NumPaymentsgt lt/FixedFloatSwa
pgt
This document declares itself as conforming to
this dtd.
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The FixedFloatSwap.dtd
lt?xml version"1.0" encoding"utf-8"?gt lt!ELEMENT
FixedFloatSwap (Notional, Fixed_Rate, NumYears,

NumPayments) gt lt!ELEMENT Notional (PCDATA)
gt lt!ELEMENT Fixed_Rate (PCDATA) gt lt!ELEMENT
NumYears (PCDATA) gt lt!ELEMENT NumPayments
(PCDATA) gt
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The FixedFloatSwap.dtd
lt?xml version"1.0" encoding"utf-8"?gt lt!ELEMENT
FixedFloatSwap (Notional, Fixed_Rate, NumYears,

NumPayments) gt
A document that conforms to this dtd must have
these elements in this order.
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The FixedFloatSwap.dtd
The tag names in the xml document.
The content of each element
lt!ELEMENT Notional (PCDATA) gt lt!ELEMENT
Fixed_Rate (PCDATA) gt lt!ELEMENT NumYears
(PCDATA) gt lt!ELEMENT NumPayments (PCDATA) gt
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Before we validate we have to cover some more Java

• Inner classes
• Exception Handling

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Inner Classes

• Nested Top Level Classes (not inner)
• Member Classes
• Local Classes
• Anonymous Classes

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Nested Top Level Class

• Nested top-level classes are not inner classes.
• Use as a convenient way to group related classes
• Since the class must be static and has no 'this'
  pointer, it
• has no access to the instance data of objects
  for its
• enclosing class.
• It behaves just like a 'normal' class or
  interface.

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//NestedTopLevelExample.java class Top
int i,j static class SomeClass //
static makes it top-level nested
int k SomeClass()
System.out.println("Constructi
ng SomeClass")
void foo() System.out.println("Hello")
Top()
System.out.println("Constructing a Top object")

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public class NestedTopLevelExample
public static void main(String args)
Top myTop new Top()
Top.SomeClass myObject new Top.SomeClass()
myObject.foo()
Output Constructing a Top object Constructing
SomeClass Hello
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Member Classes

• Member classes (there is no such thing as a
  'member
• interface)
• This inner class (it's not a top-level class)
  has no static
• keyword and can access the members of each
  object of
• its outer class.
• The class 'appears in every instance'.

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• The parent class must declare an instance of an
  inner class, before it can invoke the inner
  class methods, assign to data fields (including
  private ones), and so on.
• Unlike nested top-level classes, inner classes
  are not directly part of a package and are not
  visible outside the class in which they are
  nested.
• Inner classes are often used for GUI event
  handlers.

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// MemberClassExample.java class Top int
i 33 public class SomeClass
// access the outer object's state.
private int k i
SomeClass()
System.out.println("Constructing SomeClass")
void foo()
System.out.println("Hello")
Top() System.out.println("Cons
tructing a Top object")
SomeClass sc new SomeClass()
System.out.println(sc.k)
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public class MemberClassExample public
static void main(String args) Top
myObject new Top() //
OUTPUT Constructing a Top object Constructing
SomeClass 33
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Local Classes

• A Local class is an inner class. Typically, a
  local class
• is declared within a method. It is not a member
  of an
• enclosing class. It is visible only within the
  block.
• These classes are used primarily as "adapter
  classes".
• For example, a block of code that creates a
  Button object
• could use a local class to define a simple
  implementation
• of the ActionListener Interface. Then it could
  instantiate
• this simple implementation and pass the
  resulting object
• to the button's ActionListener method, thereby
  connecting
• the button to the "callback" code that is
  executed when
• the button is pressed.

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// Local Class example class Top int i
33 Top()
System.out.println("Constructing a Top object")
// define a class within a
method class Wow
int t Wow()
System.out.println("Building a Wow")
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t 9
Wow h new Wow()
System.out.println(" h.t "
h.t) System.out.println(" i
" i)
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public class LocalExample public
static void main(String args) Top
myObject new Top() //
OUTPUT Constructing a Top object Building a Wow
h.t 9 i 8
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Anonymous Classes

• An anonymous class is refinement of inner
  classes.
• It allows you to combine the definition of the
  class
• with the instance allocation.
• Since it is instantiated in the same expression
  that defines
• it, it can only be instantiated once. This is
  very similar to
• local classes.
• When writing a simple adapter class, the choice
  between
• a named local class and an unnamed anonymous
  class
• typically comes down to a matter of style and
  code clarity,
• rather than any difference in functionality.
• The new class can't have a constructor.

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// Anonymous.java interface SmallClass
public void foo() class Top int i
33 void someMethod(SmallClass s)
s.foo() void anotherMethod()
someMethod(new SmallClass()
public void foo()
System.out.println(
"Really fun")
)
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Top()
System.out.println("Constructing a Top object")
someMethod(new SmallClass()
public void foo()
System.out.println("
Strange but fun")
)

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public class Anonymous public static
void main(String args) // We
can't create interface objects //
error SmallClass s new SmallClass()
Top myObject new Top()
myObject.anotherMethod() //
OUTPUT Constructing a Top object Strange but
fun Really fun
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Validating two Agreement.xml files
import java.io.File import org.w3c.dom. import
javax.xml.parsers.DocumentBuilderFactory import
javax.xml.parsers.DocumentBuilder import
org.xml.sax.SAXException import
org.xml.sax.SAXParseException
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Validating two Agreement.xml files
// imports as before
Are both xml files on the command line?
public class Simulator4 public static void
main(String argv)
if(argv.length ! 2 ) System.err.println("usag
e java Simulator4
document1Name document2Name")
System.exit(1)
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Validating two Agreement.xml files
try DocumentBuilderFactory
docBuilderFactory
DocumentBuilderFactory.newInstance()
docBuilderFactory.set
Validating(true)
docBuilderFactory.setNamespaceAware(true)
DocumentBuilder docBuilder
docBuilderFactory.newD
ocumentBuilder()
This factory will produce parsers that validate!
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docBuilder.setErrorHandler( new
org.xml.sax.ErrorHandler() public
void fatalError(SAXParseException e) throws
SAXException public void
error(SAXParseException e) throws
SAXParseException
throw e public void
warning(SAXParseException err) throws
SAXParseException
System.out.println(" Warning"
", line "
err.getLineNumber()
", uri " err.getSystemId())
System.out.println("
" err.getMessage())
) Document
doc1 docBuilder.parse(new File(argv0)) Docume
nt doc2 docBuilder.parse(new File(argv1))
The new object to handle validation errors
End of method call
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docBuilder.setErrorHandler( new
org.xml.sax.ErrorHandler() public
void fatalError(SAXParseException e) throws
SAXException public void
error(SAXParseException e) throws
SAXParseException
throw e public void
warning(SAXParseException err) throws
SAXParseException
System.out.println(" Warning"
", line "
err.getLineNumber()
", uri " err.getSystemId())
System.out.println("
" err.getMessage())
) Document
doc1 docBuilder.parse(new File(argv0)) Docume
nt doc2 docBuilder.parse(new File(argv1))
Validation errors caught here.
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Lab Exercise I would like everyone to be
checked off for writing A short Java program that
validates the agreement.xml file against the
FixedFloatSwap.dtd. If, for example, the
notional tag appears twice in the xml file your
program should display oops before terminating.