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Java: Instance Methods and Instance Fields

An instance method has a Java object passed to it as the first argument of the method call. Such a Java object typically would be created by using an extension function (for example a constructor call) or a stylesheet parameter/variable. An XSLT example of this kind would be:

<xsl:stylesheet version="1.0" exclude-result-prefixes="date"

  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"

  xmlns:date="java:java.util.Date"

  xmlns:jlang="java:java.lang">

  <xsl:param name="CurrentDate" select="date:new()"/>

  <xsl:template match="/">

      <enrollment institution-id="Altova School"
                date="{date:toString($CurrentDate)}"

                type="{jlang:Object.toString(jlang:Object.getClass( date:new() ))}">

      </enrollment>

  </xsl:template>

</xsl:stylesheet>

In the example above, the value of the node enrollment/@type is created as follows:

The result (the value of @type) will be a string having the value: java.util.Date.

An instance field is theoretically different from an instance method in that it is not a Java object per se that is passed as an argument to the instance field. Instead, a parameter or variable is passed as the argument. However, the parameter/variable may itself contain the value returned by a Java object. For example, the parameter CurrentDate takes the value returned by a constructor for the class java.util.Date. This value is then passed as an argument to the instance method date:toString in order to supply the value of /enrollment/@date.