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using JDOM 1.1 on Android's Dalvik VM
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using JDOM 1.1 on Android's Dalvik VM
by Sean Sullivan-3
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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 _______________________________________________ To control your jdom-interest membership: http://www.jdom.org/mailman/options/jdom-interest/youraddr@... |
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Re: using JDOM 1.1 on Android's Dalvik VM
by Laurent Bihanic
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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 To control your jdom-interest membership: http://www.jdom.org/mailman/options/jdom-interest/youraddr@... |
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Re: using JDOM 1.1 on Android's Dalvik VM
by Sean Sullivan-3
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Thanks for the feedback. Your suggestion sounds good to me.
Is there anybody on the JDOM dev team who can commit this enhancement to the source tree? This enhancement would allow Android developers to consume XML web services using JDOM. Sean On Wed, Nov 26, 2008 at 1:27 PM, Laurent Bihanic <laurent.bihanic@...> wrote: > > > 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)) { > ... > To control your jdom-interest membership: http://www.jdom.org/mailman/options/jdom-interest/youraddr@... |
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Re: using JDOM 1.1 on Android's Dalvik VM
by Sean Sullivan-3
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ping Is there anybody on the JDOM dev team who can commit this enhancement to the source tree? Sean On Wed, Nov 26, 2008 at 2:55 PM, Sean Sullivan <sean@...> wrote: Thanks for the feedback. Your suggestion sounds good to me. _______________________________________________ To control your jdom-interest membership: http://www.jdom.org/mailman/options/jdom-interest/youraddr@... |
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Re: using JDOM 1.1 on Android's Dalvik VM
by jhunter
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Yes, I'll be doing it.
-jh- On Dec 2, 2008, at 6:08 PM, Sean Sullivan wrote: > > ping > > > Is there anybody on the JDOM dev team who can commit this > enhancement to the source tree? > > Sean > > > On Wed, Nov 26, 2008 at 2:55 PM, Sean Sullivan > <sean@...> wrote: > Thanks for the feedback. Your suggestion sounds good to me. > > Is there anybody on the JDOM dev team who can commit this enhancement > to the source tree? > > This enhancement would allow Android developers to consume > XML web services using JDOM. > > Sean > > On Wed, Nov 26, 2008 at 1:27 PM, Laurent Bihanic > <laurent.bihanic@...> wrote: > > > > > 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)) { > > ... > > > > _______________________________________________ > To control your jdom-interest membership: > http://www.jdom.org/mailman/options/jdom-interest/ > youraddr@... _______________________________________________ To control your jdom-interest membership: http://www.jdom.org/mailman/options/jdom-interest/youraddr@... |
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Re: using JDOM 1.1 on Android's Dalvik VM
by jhunter
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Here's a diff for the change I just committed.
http://markmail.org/message/gamwpsmeieovaroq -jh- Index: JDOMException.java =================================================================== RCS file: /home/cvs/jdom/src/java/org/jdom/JDOMException.java,v retrieving revision 1.24 diff -u -r1.24 JDOMException.java --- JDOMException.java 10 Nov 2007 05:28:59 -0000 1.24 +++ JDOMException.java 10 Dec 2008 00:02:17 -0000 @@ -291,14 +291,16 @@ return ((ExceptionInInitializerError)parent).getException(); } - if (parent instanceof RemoteException) { - return ((RemoteException)parent).detail; + // The RMI classes are not present in Android's Dalvik VM, so we use reflection to access them. + + Throwable nestedException = getNestedExceptionFromField(parent, "java.rmi.RemoteException", "detail"); + if (nestedException != null) { + return nestedException; } - // These classes are not part of standard JDK 1.1 or 1.2, so we - // use reflection to access them. + // These classes are not part of standard JDK 1.1 or 1.2, so again we use reflection to access them. - Throwable nestedException = getNestedException(parent, "javax.naming.NamingException", "getRootCause"); + nestedException = getNestedException(parent, "javax.naming.NamingException", "getRootCause"); if (nestedException != null) { return nestedException; } @@ -336,4 +338,31 @@ return null; } + + // This method is similar to getNestedException() except it looks for a field instead + // of a method. + private static Throwable getNestedExceptionFromField( + Throwable parent, String className, String fieldName) { + try { + // See if this Throwable is of the desired type, by using isAssignableFrom(). + Class testClass = Class.forName(className); + Class objectClass = parent.getClass(); + if (testClass.isAssignableFrom(objectClass)) { + // Use reflection to call the specified method. + Class[] argClasses = new Class[0]; + Field field = testClass.getField(fieldName); + return (Throwable)field.get(parent); + } + } + catch(Exception ex) { + // Most likely, the desired class is not available in this VM. That's fine. + // Could be that the named field isn't of type Throwable, but that should happen + // with proper call usage. + // Even if it's caused by something else, we don't want to display an error + // here, since we're already in the process of trying to display the original + // error - another error here will just confuse things. + } + + return null; + } } On Dec 3, 2008, at 9:48 AM, Jason Hunter wrote: > Yes, I'll be doing it. > > -jh- > > On Dec 2, 2008, at 6:08 PM, Sean Sullivan wrote: > >> >> ping >> >> >> Is there anybody on the JDOM dev team who can commit this >> enhancement to the source tree? >> >> Sean >> >> >> On Wed, Nov 26, 2008 at 2:55 PM, Sean Sullivan >> <sean@...> wrote: >> Thanks for the feedback. Your suggestion sounds good to me. >> >> Is there anybody on the JDOM dev team who can commit this enhancement >> to the source tree? >> >> This enhancement would allow Android developers to consume >> XML web services using JDOM. >> >> Sean >> >> On Wed, Nov 26, 2008 at 1:27 PM, Laurent Bihanic >> <laurent.bihanic@...> wrote: >> > >> > > 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)) { >> > ... >> > >> >> _______________________________________________ >> To control your jdom-interest membership: >> http://www.jdom.org/mailman/options/jdom-interest/youraddr@... > > _______________________________________________ > To control your jdom-interest membership: > http://www.jdom.org/mailman/options/jdom-interest/ > youraddr@... _______________________________________________ To control your jdom-interest membership: http://www.jdom.org/mailman/options/jdom-interest/youraddr@... |
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