[jdom-interest] using JDOM 1.1 on Android's Dalvik VM

[Laurent Bihanic]

Hi,

 > Is there a better way to code this?  Any other comments?

Seems OK but you may wish to stick to the existing way of handling possibly 
not available exception classes in JDOMException by :
- adding a new getNestedException() method e.g. 
getNestedExceptionFromField(Throwable, String, String)
- using Class.forName() and isAssignableFrom as in :
             Class testClass = Class.forName(className);
             Class objectClass = parent.getClass();
             if (testClass.isAssignableFrom(objectClass)) {
                ...

Laurent


Sean Sullivan wrote:
> 
> I'm trying to use JDOM 1.1 on the Android 1.0 platform. 
> 
> The Android platform supports most Java 5 API's.  However, java.rmi.* 
> classes are not part of the Android platform.
> 
> When I use JDOM 1.1 on Android, I see this error:
> 
> 
> W/dalvikvm(  327): VFY: unable to resolve check-cast 98 
> (Ljava/rmi/RemoteException;) in Lorg/jdom/JDOMException;
> W/dalvikvm(  327): VFY:  rejecting opcode 0x1f at 0x003d
> W/dalvikvm(  327): VFY:  rejected 
> Lorg/jdom/JDOMException;.getNestedException 
> (Ljava/lang/Throwable;)Ljava/lang/Throwable;
> W/dalvikvm(  327): Verifier rejected class Lorg/jdom/JDOMException;
> D/AndroidRuntime(  327): Shutting down VM
> W/dalvikvm(  327): threadid=3: thread exiting with uncaught exception 
> (group=0x40010e28)
> E/AndroidRuntime(  327): Uncaught handler: thread main exiting due to 
> uncaught exception
> E/AndroidRuntime(  327): java.lang.VerifyError: org.jdom.JDOMException
> 
> 
> I looked at the JDOM source code and noticed that org.jdom.JDOMException 
> uses java.rmi.RemoteException:
> 
>         if (parent instanceof RemoteException) {
>             return ((RemoteException)parent).detail;
>         }
> 
> 
> In order for this code to run on Android, we would need to eliminate 
> java.rmi.RemoteException from JDOMException.java
> 
> One possible fix (?) is to use reflection to retrieve the "detail" field:
> 
>         if (parent.getClass().getName().startsWith("java.rmi.")) {
>             try    {
>                 Field f = parent.getClass().getField("detail");
>                 return (Throwable) f.get(parent);
>             } catch (Exception ignore) {
>                 // ignored
>             }
>         }
> 
> Using 'startsWith' is a hack. The intent is to detect 
> java.rmi.RemoteException as well as all
> subclasses of java.rmi.RemoteException from the java.rmi pacakge.
> 
>   http://java.sun.com/j2se/1.4.2/docs/api/java/rmi/RemoteException.html
> 
> Is there a better way to code this?  Any other comments?
> 
> Sean