Difference between revisions of "Java Bindings"

From BaseX Documentation
Jump to navigation Jump to search
Line 38: Line 38:
<p><b>Result:</b> <code>Error [XPTY0004]: '+' operator: number expected, string found.</code></p>  
<p><b>Result:</b> <code>Error [XPTY0004]: '+' operator: number expected, string found.</code></p>  
<div id="footer">
  &copy; 2006-10 <a href="http://www.informatik.uni-konstanz.de/en/groups/dbis" target="top">
  BaseX; DBIS, U Konstanz &nbsp;</a>
  <!-- echo "Updated on ".(gmdate('Y/m/d', filectime($_SERVER[SCRIPT_NAME]))); -->
  <a href='http://twitter.com/home?status=http%3A%2F%2Fwww.basex.org' target='_blank'><img border='0' alt='twitter' src='gfx/twitter.png'/></a>
  <a href='http://facebook.com/sharer.php?u=http%3A%2F%2Fwww.basex.org' target='_blank'><img border='0' alt='facebook' src='gfx/facebook.png'/></a>
  <a href='http://del.icio.us/post?url=http%3A%2F%2Fwww.basex.org' target='_blank'><img border='0' alt='delicio.us' src='gfx/delicious.png'/></a>

Revision as of 11:52, 6 December 2010

Java Binding

The Java Binding feature is an extensibility mechanism which allows direct calling of Java methods bound as XQuery functions and manipulation of wrapped Java objects. The following examples introduce the behavior. Please note that the namespace URI must be of the form java:fullyQualifiedClassName.

This example uses the java Math class and returns the cosine of an angle:

 declare namespace math = "java:java.lang.Math";

The next example writes 256 bytes to the file output.txt:

 declare namespace fw = "java:java.io.FileWriter";
 let $file := fw:new('output.txt')
 return (
   for $i in 0 to 255
   return fw:write($file, xs:int($i)),


The well-known try/catch construct can be used in BaseX to intercept run-time errors. This feature will also be part of the new <a href="http://www.w3.org/TR/xquery-11/#id-try-catch">XQuery 1.1 Recommendation</a>.


 try {
   1 + '2'
 } catch *($code, $desc) {
   concat('Error [', $code, ']: ', $desc)

Result: Error [XPTY0004]: '+' operator: number expected, string found.