Difference between revisions of "Java Bindings"
Line 7: | Line 7: | ||
<pre class="brush:xquery">declare namespace math = "java:java.lang.Math"; | <pre class="brush:xquery">declare namespace math = "java:java.lang.Math"; | ||
math:cos(xs:double(0)) | math:cos(xs:double(0)) | ||
− | </pre> | + | </pre> |
+ | |||
+ | Note: To call a method directly it has to be set to <code>static</code> in you java code. | ||
The next example writes 256 bytes to the file <code>output.txt</code>: | The next example writes 256 bytes to the file <code>output.txt</code>: | ||
Line 19: | Line 21: | ||
) | ) | ||
</pre> | </pre> | ||
+ | |||
+ | Note: To call the <code>write</code> method of the filewriter you have to pass a | ||
+ | filewriter-object as first parameter to the method. | ||
==Try/Catch== | ==Try/Catch== |
Revision as of 11:55, 4 January 2011
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"; math:cos(xs:double(0))
Note: To call a method directly it has to be set to static
in you java code.
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($i)), fw:close($file) )
Note: To call the write
method of the filewriter you have to pass a
filewriter-object as first parameter to the method.
Try/Catch
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 XQuery 1.1 Recommendation.
Example:
try { 1 + '2' } catch *($code, $desc) { concat('Error [', $code, ']: ', $desc) }
Result: Error [XPTY0004]: '+' operator: number expected, string found.