NoClassDefFoundError: com/sun/mail/util/SharedByteArrayInputStream

problem:
when trying to send mail i get error: NoClassDefFoundError: com/sun/mail/util/SharedByteArrayInputStream

solution:
get mail.jar and put it on your classpath

http://java.sun.com/products/javamail/downloads/index.html

Java: find nested balanced tags

Problem:
I needed to parse out some divs from a html page, and java's regex cant do it. atleast when you have arbitrary number of nested balanced elements.

Solution:
<br /><br />private String removeDivContents(String id, String clazz,<br /> String text){<br />String div = "<div class="\"><br /> +clazz.toLowerCase()+"\" id=\""+id.toLowerCase()+"\">";<br />String textl = text.toLowerCase();<br />int index = textl.indexOf(div);<br />if(index == -1){<br /> return text;<br />}<br />int loc = index + div.length();<br />int end = findBalancedClosingTag(loc, textl,<br /> "<div","</div>", 1);<br />return text.substring(0,index) + text.substring(end);<br />}<br /><br />private int findBalancedClosingTag(int start,<br />String textl, String startTag, String endTag, int unClosedStarts){<br />int index = textl.indexOf(endTag,start);<br />if(index == -1){<br /> return start;<br />}<br />Pattern p = Pattern.compile(startTag);<br />Matcher m = p.matcher(textl.substring(start, index));<br />unClosedStarts --; // we are in this function so we closed ONE start tag<br />while(m.find()){<br /> unClosedStarts ++;<br />}<br />if(unClosedStarts == 0){<br /> return index + endTag.length();<br />} else {<br /> return findBalancedClosingTag(index + endTag.length(), textl, startTag, endTag, unClosedStarts);<br />}<br />}<br />
Use at your own risk.

UNIX: dd trick to speed up disk access times

This was stolen from the Lucene mailing list as a strategy to warm up an IndexSearcher:
Something like dd if=/path/to/index/foo.cfs of=/dev/null
Basically, force the data through the kernel preemptively, so FS caches it.
Run vmstat while doing it, and if the index hasn't been cached by the FS, you should see a spike in IO activity while dd is running.

source: (something in the middle of the thread)
http://www.gossamer-threads.com/lists/lucene/java-user/43418

java.lang.NoSuchFieldError:prohibited Lucene Highligher

Problem:

java.lang.NoSuchFieldError: prohibited
    at
org.apache.lucene.search.highlight.QueryTermExtractor
.getTermsFromBooleanQuery(QueryTermExtractor.java:91)

Solution:

You are using an old (pre 1.9) highlighter lib on a
1.9+ lucene. You need to pull the latest highlighter
sources from the svn repos, make a jar out of them and
use that inst

also, 'prohibited' referes to actual method param inside
of highlighter. 

nice regex util class, replaceAll

elliotth.blogspot.com/java-implementation-of-rubys-gsub.html

Here is an example of what this does:

String result = new Rewriter("([0-9]+) US cents") {
public String replacement() {
  long dollars = Long.parseLong(group(1))/100;
     return "$" + dollars;
  }
}.rewrite("5000 US cents");
System.out.println(result);

prints>> $50

nice!

java.io.IOException: read past EOF on Lucene

Problem:
This is the error:
java.io.IOException: read past EOF

Lucene throws that error when you try to read an index.

Solution:
The lucene index was most likely corrupted at some point. In my case, it broke during the ant's copy in the deployment.

Other pages say that it may be because the index uses a weird char set where chars may be bigger or smaller then what you think they are, so if you think they are 8 bits, and they are actually 7, you will read past EOF.