How do I pass a class to a method in Nashorn?

java-8, nashorn

Solution

Use `.class`:

var provider = resource.as(org.apache.tools.ant.types.resources.FileProvider.class);

or

var provider = resource.as(Java.type("org.apache.tools.ant.types.resources.FileProvider").class);

Just like in Java :-)

Problem

One of our scripts has the following line, calling a method in Ant to get a provider: ``` var provider = resource.as(org.apache.tools.ant.types.resources.FileProvider); ``` Since updating to Java 8, this now fails with an error: ``` java.lang.ClassCastException: Cannot cast jdk.internal.dynalink.beans.StaticClass to java.lang.Class at sun.invoke.util.ValueConversions.newClassCastException(ValueConversions.java:461) at sun.invoke.util.ValueConversions.castReference(ValueConversions.java:456) at jdk.nashorn.internal.scripts.Script$\^eval\_.getFileHack(<eval>:131) at jdk.nashorn.internal.scripts.Script$\^eval\_.runScript(<eval>:207) ``` I'm trying to figure out what has changed from the Nashorn docs, but it isn't particularly clear. The following change to use what I see in the documented examples gives the same error: ``` var provider = resource.as(Java.type("org.apache.tools.ant.types.resources.FileProvider")); ``` How do I convert a StaticClass to a Java Class to pass it in here?

Original source