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javaclassloadersystem-properties

How can I make XPathFactory newInstance fail in Java?

Documentation for XPathFactory.newInstance(String uri) is here.

I am trying to make this fail like this: 

println(System.getProperty("DEFAULT_PROPERTY_NAME"));
System.setProperty("DEFAULT_PROPERTY_NAME", "dummy");
println(System.getProperty("DEFAULT_PROPERTY_NAME"));
XPathFactory xPathFactory = XPathFactory.newInstance();
println(xPathFactory.getClass());

The output I am getting is :

null
dummy
class org.apache.xpath.jaxp.XPathFactoryImpl

I am expecting that the ClassLoader will fail due to the bullet point:

If the system property DEFAULT_PROPERTY_NAME + ":uri" is present, where uri is the parameter to this method, then its value is read as a class name. The method will try to create a new instance of this class by using the class loader, and returns it if it is successfully created.

but that is not the case and I am obviously missing something.

What am I doing wrong?

Solution

  • I am expecting that the ClassLoader will fail due to the bullet point:

    This bullet point refers to method:

    public static final XPathFactory newInstance(String uri)

    But you are calling:

    public static final XPathFactory newInstance()

    which states:

    This method is functionally equivalent to:

    newInstance(DEFAULT_OBJECT_MODEL_URI)

    Since the implementation for the W3C DOM is always available, this method will never fail.