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<h1>Calling Static Methods in a Java Class</h1>
<p><b>Static methods</b> can be called directly.</p>
<p>For example (in XSLT):</p>
<div class="codeblock"
style="border: solid thin; background-color: #B1CCC7; padding: 2px">
<pre>
<code><xsl:value-of select="math:sqrt($arg)"
xmlns:math="java:java.lang.Math"/>
</code>
</pre>
</div>
<p>This will invoke the static method <code>java.lang.Math#sqrt()</code>, applying it to the value of the variable
<code>$arg</code>, and copying the value of the square root of <code>$arg</code> to the result tree.</p>
<p>Similarly (in XQuery):</p>
<div class="codeblock"
style="border: solid thin; background-color: #B1CCC7; padding: 2px">
<pre>
<code><a xmlns:double="java:java.lang.Double">
{double:MAX_VALUE()} </a>
</code>
</pre>
</div>
<p>This will output the value of the static field <code>java.lang.Double#MAX_VALUE</code>. (In practice, it
is better to declare the namespace in the query prolog, because it will then not be copied to the result tree.)</p>
<p>A static Java method called as an extension function may have an extra first argument of
class <a class="bodylink" href="../../javadoc/net/sf/saxon/expr/XPathContext.html"><code>net.sf.saxon.expr.XPathContext</code></a>.
This argument is not
supplied by the calling XPath or XQuery code, but by Saxon itself.
The <code>XPathContext</code> object provides methods to access many
internal Saxon resources, the most useful being <code>getContextItem()</code> which returns the context item
from the dynamic context. The XPathContext object is available with static or instance-level methods, but
not with constructors.</p>
<p>The following example shows a function that obtains the line number of the context node (this is actually
a built-in Saxon extension):</p>
<div class="codeblock"
style="border: solid thin; background-color: #B1CCC7; padding: 2px">
<pre>
<code> /**
* Return the line number of the context node.
*/
public static int lineNumber(XPathContext c) {
Item item = c.getCurrentIterator().current();
if (item instanceof NodeInfo) {
return ((NodeInfo)item).getLineNumber();
} else {
return -1;
}
}</code>
</pre>
</div>
<p>If this method appears in class <code>com.example.code.NodeData</code>, then it can be accessed
using the following code in XSLT:</p>
<div class="codeblock"
style="border: solid thin; background-color: #B1CCC7; padding: 2px">
<pre>
<code><xsl:value-of select="nd:line-number()"
xmlns:nd="java:com.example.code.NodeData"/></code>
</pre>
</div>
<p>or the following in XQuery:</p>
<div class="codeblock"
style="border: solid thin; background-color: #B1CCC7; padding: 2px">
<pre>
<code><line xmlns:nd="java:com.example.code.NodeData">
{ nd:line-number() }
</line></code>
</pre>
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