Monday, September 25, 2006

Wandering Off

I tend to wander. Be it in downtown Beijing or just reading a book.

I'm still reading Java for Artists. I made it a couple of pages in several hours. Here's a rundown of the journey.

Chapter 3 talks about the Spiral Development Cycle.


The same 3 steps (plan, code, test) are repeated to build and maintain forward progress. And although the code and testing have peristent artifacts (the code itself), the plan steps are layed out in tables in the book. Somewhere along the line I decided I wanted to be abkle to do everything in text files (Starting from scratch). I'd like continue this process after I'm done with the book, but how can I create structured data in a text file? XML. Damn it! Now I have to go read up on XML again. How many times does this make now? Use it or lose it. A google search on XML turns up a favorite site of mine (w3schools.com). Of Course, I can't just read about XML (since alone it won't really meet my needs). This leads me to tutorials on XML, XPath, XSLT and XSL-FO (that's a new one to me).

I probably shouldn't be watching tv while I'm doing all of this...

So now I'm working on the XML and XSL that I hope will make up my plan list. Java? Yeah, I'll get back to that eventually. At the moment I can't even get the XSL to properly transform the XML. I am Clearly a masochist.

Here's the xml to this point:


<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet type="text/xsl" href="RobotRat.xsl"?>

<dev_plan xmlns="http://brian.donoho.com/xml/">
 <name>RobotRat</name>
 <prog_lang>Java</prog_lang>
 <step id="1" phase="1">
   <design_consideration>
     Program Structure
   </design_consideration>
   <design_decision>
     One class will contain all the functionality
   </design_decision>
 </step>

 <step id="2" phase="1">
   <design_consideration>
     Creating the Java application class
   </design_consideration>
   <design_decision>
     The class name will be RobotRat. It will contain a “public static void main(String[] args){ }” method.
   </design_decision>
 </step>

 <step id="3" phase="1">
   <design_consideration>
     constructor method
   </design_consideration>
   <design_decision>
     Write a class constructor that will print a short message to the screen when a RobotRat object is created.
   </design_decision>
 </step>

 <step id="" phase="">
   <design_consideration>
   </design_consideration>
   <design_decision>
   </design_decision>
 </step>

 <step id="" phase="">
   <design_consideration>
   </design_consideration>
   <design_decision>
   </design_decision>
 </step>
 
</dev_plan>


And the xsl:

<?xml version="1.0" encoding="ISO-8859-1"?>

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="/">
 <html>
 <body>
   <h2><xsl:value-of select="dev_plan/name" /> Dev Plan</h2>
   <table border="1">
     <tr>
       <th>Check-Off</th>
       <th>Design Consideration</th>
       <th>Design Decision</th>
     </tr>
     <tr>
       <td></td>
       <td></td>
       <td></td>
     </tr>
     <xsl:for-each select="dev_plan/step">
     <tr>
       <td></td>
       <td><xsl:value-of select="design_consideration" /></td>
       <td><xsl:value-of select="design_decision" /></td>
     </tr>
     </xsl:for-each>
   </table>
 </body>
 </html>
</xsl:template>

</xsl:stylesheet>


After hours of trial and error. I find that removing the xmlns attribute from the dev_plan element makes everything work. Do I go and figure out why it was breaking things or do I move on with what I should be doing? ROFLOL

Before I get back to figuring out what went wrong with the xml, I should mention that I took another side trip to figure out / remember how display code on a web page. Doing a google search for displaying HTML code brought me to the xmp tag which I'd never heard of, but didn't work for me (meaning, just throwing it around the raw code didn't work). Finally I found an online tool to Display HTML sample code. Thank You Christopher Brewer ^_^

After being left unfulfilled by the explaination of XML Namespaces at w3schools (first time for everything), I found this article at xml.com. Interesting, but I still don't quite get it. Several variations on the xml still result in it not making it through the xsl. I know how to make it work, but I want to understand what's going on when it's not working. After reading Ronald Bourret's XML Namespaces FAQ I understand namespaces themselves a bit more, and get the impression that mine is declared properly, but not why the xsl "breaks".

After doing a search for "XML Namespaces breaks xslt xsl transform" I found a link to a thread that explains the problem and the solution (I didn't want). It looks like my options are to remove the default namespace from my xml doc OR prefix everything in both documents.
After a few more unsuccessful tests and in the interst of continuing my java studies I will remove the default xmlns attribute. Fortunitely this R&D won't be wasted as I will be visiting XML in a later study session.

Labels: , ,

posted by Donoho at 11:45 PM 0 comments

Tuesday, September 19, 2006

Java compile error because of text encoding

I have the magical ability to find every possible error in the course of learning about something. Take for example todays exploits. I'm developing on windows XP using Notepad++.

I'm reading "Java For Artists—The Art, Philosophy, and Science of Object-Oriented Programming" and given the simple code below:

-----------------------------------------------------------------------------------------------
Example 2.1: SampleClass.java

package com.pulpfreepress.jfa.chapter1;

import java.util.*;

public class SampleClass {
/**************************************
Class and instance field declarations
***************************************/
public static final int CONST_VAL = 25;
private static int class_variable = 0;
private int instance_variable = 0;

public SampleClass(){
System.out.println("Sample Class Lives!");
}

public static void setClassVariable(int val){
class_variable = val;
}

public static int getClassVariable(){
return class_variable;
}

public void setInstanceVariable(int val){
instance_variable = val;
}

public int getInstanceVariable(){
return instance_variable;
}
}


-----------------------------------------------------------------------------------------------
Example 2.2: ApplicationClass.java

package com.pulpfreepress.jfa.chapter1;

public class ApplicationClass {

public static void main(String args[]){
SampleClass sc = new SampleClass();
System.out.println(SampleClass.CONST_VAL);
System.out.println(SampleClass.getClassVariable());
System.out.println(sc.getInstanceVariable());
SampleClass.setClassVariable(3);
sc.setInstanceVariable(4);
System.out.println(SampleClass.getClassVariable());
System.out.println(sc.getInstanceVariable());

System.out.println(sc.getClassVariable());
}
}
-----------------------------------------------------------------------------------------------

I still got compile errors as such:
[parsing started src\com\pulpfreepress\jfa\chapter1\ApplicationClass.java]
src\com\pulpfreepress\jfa\chapter1\ApplicationClass.java:1: 'class' or 'interface' expected
package com.pulpfreepress.jfa.chapter1;
^
src\com\pulpfreepress\jfa\chapter1\ApplicationClass.java:1: illegal character: \187
package com.pulpfreepress.jfa.chapter1;
^
src\com\pulpfreepress\jfa\chapter1\ApplicationClass.java:1: illegal character: \191
package com.pulpfreepress.jfa.chapter1;
^
[parsing completed 62ms]
[parsing started src\com\pulpfreepress\jfa\chapter1\SampleClass.java]
src\com\pulpfreepress\jfa\chapter1\SampleClass.java:1: 'class' or 'interface' expected
package com.pulpfreepress.jfa.chapter1;
^
src\com\pulpfreepress\jfa\chapter1\SampleClass.java:1: illegal character: \187
package com.pulpfreepress.jfa.chapter1;
^
src\com\pulpfreepress\jfa\chapter1\SampleClass.java:1: illegal character: \191
package com.pulpfreepress.jfa.chapter1;
^
src\com\pulpfreepress\jfa\chapter1\SampleClass.java:2: 'class' or 'interface' expected
import java.util.*;
^
[parsing completed 31ms]
[total 93ms]
7 errors

After hours and several Google searches on 'class' or 'interface' expected, checking syntax, etc with no success, I wondered what the hell this: was.

Turns out, in my efforts to create files that would be usable in Unix and Windows I encoded my text files as UTF-8. Upon changing them back to Ansii they compiled without error.

Time to read up on Unicode.

Labels: ,

posted by Donoho at 6:30 PM 1 comments

Monday, September 18, 2006

Path / CLASSPATH Changes

After making changes to the System Path /CLASSPATH environment variables in Windows, close existing command prompts and open a new one for the changes to be reflected.
No comment on how long it took me to figure this out.

Labels: ,

posted by Donoho at 7:50 PM 0 comments