Segmentation Fault when using DocumentBuilderFactory through the Java Bridge in Delphi

Question

I'm trying to use javax.xml.parsers.DocumentBuilderFactory in Delphi code through the JNI/Java Bridge.

This is the interface I constructed for the factory:

Note: I know in the class the actual creation method is newInstance() but when I try using newInstance instead of init I also get the same segmentation fault.

{DocumentBuilderFactory}
JDocumentBuilderFactoryClass = interface(JObjectClass)
['{8475A5A9-F10A-4DDA-9D50-C714C015C81C}']
    function init: JDocumentBuilderFactory; cdecl; overload;
end;

[JavaSignature('javax/xml/parsers/DocumentBuilderFactory')]
JDocumentBuilderFactory = interface(JObject)
['{7F4F2927-25EB-4B03-9373-A43B0757CD06}']
    function newDocumentBuilder: JDocumentBuilder; cdecl;
end;

TJDocumentBuilderFactory = class
     (TJavaGenericImport<JDocumentBuilderFactoryClass, JDocumentBuilderFactory>)
end;

And this is the code calling the interface/object:
tmpObject: JObject;

// init an object, i have already tried just calling create
tmpObject := TJDocumentBuilderFactory.JavaClass.init;
//then wrap it into the appropriate object
if Assigned(tmpObject) then
    builderFactory := TJDocumentBuilderFactory.Wrap
        ((tmpObject as IlocalObject).GetObjectID);

As far as I know I don't have to declare every method of the java class in the interface, I have used other classes without problems.

Usually segmentation faults raised by the java bridge indicate that there is a problem loading the interface or file. For example, if the path to the java class in the java signature is wrong then that will result in a segmentation fault too. However this is not the case here since I can confirm that the path is right. I've looked around but I can't find any suggestions as to how to resolve this problem. Any ideas?

regards,
Jason

Answer 1

The segmentation fault is understandable because it is not possible to create instances of abstract classes.

The Android documentation says that DocumentBuilderFactory is an abstract class. The class provides a static method, newDocumentBuilder() , which returns a new instance of a DocumentBuilder.

To create an instance of the factory, use DocumentBuilderFactory. newInstance ().

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As I do not work with a mobile edition of Delphi, I can not say how a static factory method can be used over the JNI adapter. If it is not documented, maybe it is worth its own Stackoverflow question.