Java Bindings

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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 = "";
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 XQuery 1.1 Recommendation.


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

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