Java XStream Deep Copy raises Exception ObjectAccessException -


i have xstream cloning. here simple code, have not expertise it.

com.thoughtworks.xstream.xstream xstream = new com.thoughtworks.xstream.xstream();

later store clone instances in hashtable (i know not idea storing on legacy system).

i store class of student, later store (clone) other instance of student , raises. 

com.thoughtworks.xstream.converters.reflection.objectaccessexception: not call com.model.student_$$_javassist_83.writereplace():null java.lang.nullpointerexception

here code storing clone objects.

public void keep(string key, object value)  {     object obj = xstream.fromxml(xstream.toxml(value));     storage.put(key,obj); }

i think here source code problem arising. [xstream sources.][snippet]

 public object callwritereplace(object object)   {                            method writereplacemethod = getmethod(object.getclass(), "writereplace", null, true);               if (writereplacemethod != null) {                   try {                       object[] empty_args = new object[0];                       return writereplacemethod.invoke(object, empty_args);                   } catch (illegalaccessexception e) {                       throw new objectaccessexception("could not call " + object.getclass().getname() + ".writereplace()", e);                   } catch (invocationtargetexception e) {                       throw new objectaccessexception("could not call " + object.getclass().getname() + ".writereplace()", e.gettargetexception());                   }              } else {                   return object;               }                     }

i hope can guide me, little lost on topic.

here trace. seems when clean dependences of clazz example student.setlistofphones(null) works; exception throw on 2 or 3 level in graph. why according xstream says:

making suitable large object graphs or systems high message throughput.

stack trace:

com.thoughtworks.xstream.converters.reflection.objectaccessexception: not call com.model.subjects_$$_javassist_224.writereplace() : null java.lang.nullpointerexception @ javassist.util.proxy.runtimesupport$defaultmethodhandler.invoke(runtimesupport.java:37) @ com.model.subjects_$$_javassist_224.writereplace(subject_$$_javassist_224.java) @ sun.reflect.nativemethodaccessorimpl.invoke0(native method) @ sun.reflect.nativemethodaccessorimpl.invoke(nativemethodaccessorimpl.java:39) @ sun.reflect.delegatingmethodaccessorimpl.invoke(delegatingmethodaccessorimpl.java:25) @ java.lang.reflect.method.invoke(method.java:597) @ com.thoughtworks.xstream.converters.reflection.serializationmethodinvoker.callwritereplace(serializationmethodinvoker.java:88) @ com.thoughtworks.xstream.converters.reflection.abstractreflectionconverter.marshal(abstractreflectionconverter.java:60) @ com.thoughtworks.xstream.core.abstractreferencemarshaller.convert(abstractreferencemarshaller.java:69) @ com.thoughtworks.xstream.core.treemarshaller.convertanother(treemarshaller.java:58) @ com.thoughtworks.xstream.core.abstractreferencemarshaller$1.convertanother(abstractreferencemarshaller.java:84) @ com.thoughtworks.xstream.converters.reflection.abstractreflectionconverter.marshallfield(abstractreflectionconverter.java:229) @ com.thoughtworks.xstream.converters.reflection.abstractreflectionconverter$2.writefield(abstractreflectionconverter.java:208) @ com.thoughtworks.xstream.converters.reflection.abstractreflectionconverter$2.<init>(abstractreflectionconverter.java:171) @ com.thoughtworks.xstream.converters.reflection.abstractreflectionconverter.domarshal(abstractreflectionconverter.java:116) @ com.thoughtworks.xstream.converters.reflection.abstractreflectionconverter.marshal(abstractreflectionconverter.java:72) @ com.thoughtworks.xstream.core.abstractreferencemarshaller.convert(abstractreferencemarshaller.java:69) @ com.thoughtworks.xstream.core.treemarshaller.convertanother(treemarshaller.java:58) @ com.thoughtworks.xstream.core.abstractreferencemarshaller$1.convertanother(abstractreferencemarshaller.java:84)

hi have solved problem method creating shallow copy on class student , of course when xstream got class relationship wasn't deep enough xstream , nullpointerexception throw.. thank dave god bless.


Comments

Post a Comment

Popular posts from this blog

linux - xterm copying to CLIPBOARD using copy-selection causes automatic updating of CLIPBOARD upon mouse selection -

i've tried various ways coerce xterm (versions 285 , 292) copy selection clipboard clipboard whenever press ctrl-shift-c. promising way far has been, in ~/.xresources, put this: xterm*vt100.translations: #override \ ctrl shift <keypress> c: copy-selection(clipboard) \n\ ctrl shift <keypress> v: insert-selection(clipboard) ctrl-shift-v works perfectly, copying has nuance... if restart xterm, highlighting text puts things in primary clipboard; expected, proper, default behavior. if hit ctrl-shift-c, copies current selection clipboard clipboard. the bug, however, if highlight text after first time pressed ctrl-shift-c, you'll see highlighting copies both primary and clipboard. cannot figure out how stop xterm updating clipboard upon selection... , doesn't make sense me in first place. i said, @ specific point in time, copy selection clipboard... yet starts updating automatically upon selection after doing once... anyone have workaround...
Read more

c++ - qgraphicsview horizontal scrolling always has a vertical delta -

Image
i've subclassed qgraphicsview custom canvas used in cad application. i've reimplemented qgraphicsview::wheelevent check keyboard modifiers control key and, if control key pressed, zoom. i'm trying implement horizontal scroll when user holds shift , uses wheel. the problem i'm having horizontal scrolling always scrolls 0.279. not huge problem, hugely annoying , points else being wrong. so, here questions: is right way implement horizontal scrolling? if not, is? how eliminate delta of 0.279? thanks in advance. code , sample output below void myview::zoom(int delta) { double factor = pow(1.2, delta/abs(delta)); this->scale(factor, factor); } void myview::scrollhorizontal(int level) { qpointf center = maptoscene(viewport()->rect().center()); qdebug() << "center: " << center.x() << ", " << center.y(); centeron(qpointf(center.x() - level, center.y())); } void myview::wheelevent(qwheeleve...
Read more