*Written in java USING eclipse IDE* - I have finished most ofthe code but cannot figure out why I am getting this error:

Exception in thread "main" java.lang.AssertionError: Violationof: k < the number of subtrees of the root of this

at components.xmltree.XMLTree1.child(SourceFile:293)

at RSSAggregator.processItem(RSSAggregator.java:284)

at RSSAggregator.outputHeader(RSSAggregator.java:179)

at RSSAggregator.processFeed(RSSAggregator.java:90)

at RSSAggregator.indexOutputHeader(RSSAggregator.java:56)

at RSSAggregator.main(RSSAggregator.java:342)

The problem can be locatedat: http://web.cse.ohio-state.edu/software/2221/web-sw1/assignments/projects/rss-aggregator/rss-aggregator.html

Use this feed totest: http://glengainer.com/CSE2221-RSS_Feeds/metaRSSFeedsXML_sampleNews.xml

My code so far:

import components.simplereader.SimpleReader;
import components.simplereader.SimpleReader1L;
import components.simplewriter.SimpleWriter;
import components.simplewriter.SimpleWriter1L;
import components.xmltree.XMLTree;
import components.xmltree.XMLTree1;

/**
* Program to convert an XML RSS (version 2.0) feed from agiven URL into the
* corresponding HTML output file.
*
* @author Erik Anderson
*
*/
public final class RSSAggregator {

/**
* Private constructor so this utility classcannot be instantiated.
*/
private RSSAggregator() {
}

/**
* Outputs the "opening" tags in the generatedHTML file. These are the
* expected elements generated by thismethod:
*
*
*

* list of feeds for the index page link
*

*
*
* @param feeds
* thefeeds element XMLTree
* @param out
* theoutput stream
* @updates out.content
* @requires [the root of channel is a tag] and out.is_open
* @ensures out.content = #out.content * [theHTML "opening" tags]
*/
private static void indexOutputHeader(XMLTree feeds,SimpleWriter out) {

String title =feeds.attributeValue("title");

out.println("");
out.println("");
out.println("");
out.println(title);
out.println("");
out.println("");
out.println("

");

for (int i = 0;feeds.numberOfChildren() > i; i++) {
if(feeds.child(i).isTag()
&& feeds.child(i).label().equals("feed")) {
processFeed(feeds.child(i).attributeValue("url"),
feeds.child(i).attributeValue("file"),out);
out.println("

• + feeds.child(i).attributeValue("url") +"">"
  + feeds.child(i).attributeValue("name") +"
");
}

}
out.println("

");
out.println("");
out.println("");
}

/**
* Processes one XML RSS (version 2.0) feed froma given URL converting it
* into the corresponding HTML outputfile.
*
* @param url
* theURL of the RSS feed
* @param file
* thename of the HTML output file
* @param out
* theoutput stream to report progress or errors
* @updates out.content
* @requires out.is_open
* @ensures

     * [reads RSS feed from url, saves HTML documentwith table of news items
     *   to file, appends to out.contentany needed messages]
     * 


*/
private static void processFeed(String url, Stringfile, SimpleWriter out) {
XMLTree xml = new XMLTree1(url);
SimpleWriter fileOut = newSimpleWriter1L(file);

outputHeader(xml.child(0),fileOut);
outputFooter(fileOut);
}

/**
* Outputs the "opening" tags in the generatedHTML file. These are the
* expected elements generated by thismethod:
*
*
*
*

the page title inside a link to the link
*


*


* the channel description
*


*
*
*
*
*
*
*
* @param channel
* thechannel element XMLTree
* @param out
* theoutput stream
* @updates out.content
* @requires [the root of channel is a tag] and out.is_open
* @ensures out.content = #out.content * [theHTML "opening" tags]
*/
private static void outputHeader(XMLTree channel,SimpleWriter out) {
assert channel != null : "Violation of:channel is not null";
assert out != null : "Violation of: outis not null";
assert channel.isTag() &&channel.label().equals("channel") : ""
+"Violation of: the label root of channel is a tag";
assert out.isOpen() : "Violation of:out.is_open";

/*
* Assigns title variable eitherdata from 'title' child, or
* 'description child if 'title'is empty. If neither exist, assigns
* value of "No information" totitle.
*/
String title = "";
if (getChildElement(channel, "title")> 0) {
title =channel.child(getChildElement(channel, "title")).label();
} else if (getChildElement(channel,"description") > 0) {
title =channel.child(getChildElement(channel, "description"))
.label();
} else {
title = "Noinformation";
}

/*
* runs getChildElement to assignvalue to String description. If there
* is no description value, "NoDescription" is assigned to the
* description string
*/
String description = "";
if(channel.child(getChildElement(channel, "description"))
.numberOfChildren() < 1) {
description = "NoDescription.";
} else {
description =channel.child(getChildElement(channel, "description"))
.child(0).label();
}

// Prints all the necessary htmlformat to the outfile
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");
out.println(
"

+ channel.child(getChildElement(channel,"link"))
.child(0).label()
+ "">" + title +"

");
out.println("

" + description +"

");
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");

// Goes through each of 'channel'children and creates a table in html via the processItemmethod
int i = 0;
while (channel.numberOfChildren() >i) {
if(channel.child(i).label().equals("item")) {
processItem(channel.child(i), out);
}
i++;
}

}

/**
* Finds the first occurrence of the given tagamong the children of the
* given {@code XMLTree} and return its index;returns -1 if not found.
*
* @param xml
* the{@code XMLTree} to search
* @param tag
* thetag to look for
* @return the index of the first child of typetag of the {@code XMLTree}
* or -1 if notfound
* @requires [the label of the root of xml is atag]
* @ensures

     * getChildElement =
     *  [the index of the first child of typetag of the {@code XMLTree} or
     *   -1 if not found]
     * 


*/
private static int getChildElement(XMLTree xml,String tag) {
assert xml != null : "Violation of: xmlis not null";
assert tag != null : "Violation of: tagis not null";
assert xml.isTag() : "Violation of: thelabel root of xml is a tag";

/*
* If xml has an attribute called'tag', it will provide the index value
* for the position of the 'tag'attribute. If there is no attribute
* called 'tag', then it returns-1.
*/
int i = xml.numberOfChildren(), index =-1;

while (i > 0 && index< 0) {
i--;
if(xml.child(i).label().equals(tag)) {
index =i;
}
}

return index;
}

/**
* Processes one news item and outputs one tablerow. The row contains three
* elements: the publication date, the source,and the title (or
* description) of the item.
*
* @param item
* thenews item
* @param out
* theoutput stream
* @updates out.content
* @requires

     * [the label of the root of item is an tag] and out.is_open
     * 


* @ensures

     * out.content = #out.content *
     *   [an HTML table row withpublication date, source, and title of news item]
     * 


*/
private static void processItem(XMLTree item,SimpleWriter out) {
assert item != null : "Violation of:item is not null";
assert out != null : "Violation of: outis not null";
assert item.isTag() &&item.label().equals("item") : ""
+"Violation of: the label root of item is an tag";
assert out.isOpen() : "Violation of:out.is_open";

out.println("

");

// pubDate string is assigned avalue if pubDate returns a value, otherwise it is assigned a valueof "No Date Available"
String pubDate = "";
if (item.child(getChildElement(item,"pubDate"))
.numberOfChildren() < 1) {
pubDate = "No DateAvailable";
} else {
pubDate =item.child(getChildElement(item, "pubDate")).child(0)
.label();
}
out.println("

");

// source string is assigned a valueif a label of one of item's children returns a value "source",otherwise it is assigned an empty value. The results are thenprinted to the outfile
String source = "No SourceAvailable.";
String sourceURL = "";
int i = 0, x = -1;
while (item.numberOfChildren() > i){
if(item.child(i).label().equals("source")) {
source =item.child(i).child(0).label();
sourceURL =item.child(i).attributeValue("url");
out.println("

");
x =0;
}
i++;
}
if (x != 0) {
out.println("");
}

// news string is assigned a valueif "description" returns a value greater than 1 fromgetChildElement. If "description" does not return a value, "title"will be run in getChildElement.If neither return any value, thedefault "No description" will be printed
String news = "No description";
if (getChildElement(item,"description") > 0) {
news =item.child(getChildElement(item, "description")).child(0)
.label();
} else if (getChildElement(item,"title") > 0) {
news =item.child(getChildElement(item, "title")).child(0).label();
}

String link = "";
if (getChildElement(item, "link") >0) {
link =item.child(getChildElement(item, "link")).child(0).label();
}

out.println("

");
out.println("");
}

/**
* Outputs the "closing" tags in the generatedHTML file. These are the
* expected elements generated by thismethod:
*
*

Date	Source	News
Date	Source	News
" + pubDate +"	" +source + "	"+ source + "	" + news + "


*
*
* @param out
* theoutput stream
* @updates out.contents
* @requires out.is_open
* @ensures out.content = #out.content * [theHTML "closing" tags]
*/
private static void outputFooter(SimpleWriter out){
assert out != null : "Violation of: outis not null";
assert out.isOpen() : "Violation of:out.is_open";

// Prints the closing html data tothe outfile
out.println("");
out.println("");
out.println("");
}

/**
* Main method.
*
* @param args
* thecommand line arguments; unused here
*/
public static void main(String[] args) {
SimpleReader in = newSimpleReader1L();
SimpleWriter out = newSimpleWriter1L();

// Requests user input xml file thatcontains url feeds and then asks user to name output file.
out.print("Please enter a XML file withURL feeds: ");
String inputXML = in.nextLine();
XMLTree xml = newXMLTree1(inputXML);

out.print("Please name the outputfile: ");
String outfileName = in.nextLine();

SimpleWriter fileOut = newSimpleWriter1L(outfileName);

indexOutputHeader(xml, fileOut);

in.close();
out.close();
}

}