I would honestly suspect that it's "meant" to be this way, and perhaps the documentation is buggy. If you want, posting a bug report might get some action by Android devs, if none of them respond here.
Kris On Wed, Oct 30, 2013 at 3:39 PM, Palmer Eldritch <[email protected]> wrote: > I did not mean to complain at Nobu - sorry if I sounded harsh :) > > I just wanted to point out that my question was not so much what happens but > why - and also raise awareness to this buggy and unintuitive behavior- or > maybe have someone explain why this is so. > > Should we post a bug report ? > > > On Wednesday, October 30, 2013 8:23:46 PM UTC+2, Kristopher Micinski wrote: >> >> Your question seems more to deal with intention rather than >> complaining. I believe that Nobu's response was merely interpreting >> the implementation and trying to interpret it, so there's no use in >> trying to complain at him for providing a guess at something he didn't >> even write. >> >> kris >> >> >> On Wed, Oct 30, 2013 at 2:02 PM, Palmer Eldritch <[email protected]> >> wrote: >> > >> > On Wednesday, October 30, 2013 7:44:17 PM UTC+2, Nobu Games wrote: >> >> >> >> I quickly peeked into the source code and well, this is the way how it >> >> is >> >> programmed. When an exception occurs while the preferences data file >> >> gets >> >> read, SharedPreferences sets internally an empty map so you start from >> >> scratch. I even dug a bit deeper. The XML serializer just ignores NULL >> >> keys >> >> and creates XML output that cannot be properly read anymore through the >> >> map >> >> deserialization method which seems to expect an existing key value. >> > >> > >> > My question is really why was it allowed to insert a null key in the >> > first >> > place - why not throw a NPE immediately (and say so in the docs) ? >> > If you read my links (point 3 here) you will see that null keys are >> > perfectly valid : - they fail only on loading the prefs - taking down >> > everything with them >> > They should either fix deserialization or prohibit null keys >> >> >> >> >> >> As for why it has been programmed like that... I think the reasoning >> >> may >> >> be that preferences are not deemed to be of so much importance that it >> >> should make the app crash in case of failure. This error state is >> >> silently >> >> discarded and you start over with the defaults. I think that's a >> >> reasonable >> >> approach since any app should be able to start over with empty >> >> preferences. >> > >> > >> > >> > Not at all - Shared Preferences is a documented persistence mechanism - >> > it >> > is as reasonable as deleting a database without even saying so >> > >> >> >> >> >> >> In this particular case you may have discovered a tiny bug you may want >> >> to >> >> report. But to be honest, using null keys is a pretty unusual thing to >> >> do. >> > >> > >> > Not so (either by mistake or not). >> > See the discussions in the SO. Some more I suspect they may have to do >> > with >> > null keys : >> > >> > sharedpreferences - Android - Shared Preferences are lost sometimes - >> > Stack >> > Overflow >> > >> > http://stackoverflow.com/questions/7943573/android-shared-preferences-are-lost-sometimes >> > android - Shared Preferences get lost after shutting down device or >> > killing >> > the app - Stack Overflow >> > >> > http://stackoverflow.com/questions/9803838/shared-preferences-get-lost-after-shutting-down-device-or-killing-the-app#comment12495021_9803838 >> > >> >> >> >> >> >> On Wednesday, October 30, 2013 5:48:12 AM UTC-5, Palmer Eldritch wrote: >> >>> >> >>> The preferences are apparently cleared when one tries to load them >> >>> when >> >>> there is a null key which is bad ! Reproducer : >> >>> >> >>> public class XmlExceptionTest extends AndroidTestCase { >> >>> /** Run it twice - on the second run the exception is thrown >> >>> */ >> >>> public void testXmlException() { >> >>> Context ctx = getContext(); >> >>> SharedPreferences prefs = PreferenceManager >> >>> .getDefaultSharedPreferences(ctx); // exception thrown >> >>> here (line 18) >> >>> // and apparently it clears the prefs as the condition >> >>> below >> >>> is false >> >>> if (prefs.contains("run_once")) { // false >> >>> Log.w("XmlExceptionTest", >> >>> "contains null key :" + prefs.contains(null)); >> >>> } >> >>> Editor e = prefs.edit(); >> >>> e.putBoolean("run_once", true).commit(); >> >>> e.putString(null, "I put a sting with null key").commit(); >> >>> assertTrue("Contains null", prefs.contains(null)); >> >>> PreferenceManager.getDefaultSharedPreferences(ctx); // >> >>> exception >> >>> // NOT thrown here - why ? - apparently there is a static >> >>> factory >> >>> // returning the instance it already constructed >> >>> // e.clear().commit(); // this eliminates the exception >> >>> } >> >>> } >> >>> >> >>> exception : >> >>> >> >>> W/ApplicationContext(): getSharedPreferences >> >>> W/ApplicationContext(): org.xmlpull.v1.XmlPullParserException: Map >> >>> value without name attribute: string >> >>> W/ApplicationContext(): at >> >>> com.android.internal.util.XmlUtils.readThisMapXml(XmlUtils.java:521) >> >>> W/ApplicationContext(): at >> >>> com.android.internal.util.XmlUtils.readThisValueXml(XmlUtils.java:733) >> >>> W/ApplicationContext(): at >> >>> com.android.internal.util.XmlUtils.readValueXml(XmlUtils.java:667) >> >>> W/ApplicationContext(): at >> >>> com.android.internal.util.XmlUtils.readMapXml(XmlUtils.java:470) >> >>> W/ApplicationContext(): at >> >>> android.app.ContextImpl.getSharedPreferences(ContextImpl.java:361) >> >>> W/ApplicationContext(): at >> >>> >> >>> android.preference.PreferenceManager.getDefaultSharedPreferences(PreferenceManager.java:348) >> >>> W/ApplicationContext(): at >> >>> >> >>> gr.uoa.di.android.helpers.test.XmlExceptionTest.testXmlException(XmlExceptionTest.java:18) >> >>> W/ApplicationContext(): at >> >>> java.lang.reflect.Method.invokeNative(Native Method) >> >>> W/ApplicationContext(): at >> >>> java.lang.reflect.Method.invoke(Method.java:521) >> >>> W/ApplicationContext(): at >> >>> junit.framework.TestCase.runTest(TestCase.java:154) >> >>> W/ApplicationContext(): at >> >>> junit.framework.TestCase.runBare(TestCase.java:127) >> >>> W/ApplicationContext(): at >> >>> junit.framework.TestResult$1.protect(TestResult.java:106) >> >>> W/ApplicationContext(): at >> >>> junit.framework.TestResult.runProtected(TestResult.java:124) >> >>> W/ApplicationContext(): at >> >>> junit.framework.TestResult.run(TestResult.java:109) >> >>> W/ApplicationContext(): at >> >>> junit.framework.TestCase.run(TestCase.java:118) >> >>> W/ApplicationContext(): at >> >>> android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:169) >> >>> W/ApplicationContext(): at >> >>> android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:154) >> >>> W/ApplicationContext(): at >> >>> >> >>> android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:520) >> >>> W/ApplicationContext(): at >> >>> >> >>> android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1447) >> >>> >> >>> Posted in SO here and in the relevant thread here - but still no >> >>> answers >> >>> >> >>> Any ideas ? >> > >> > -- > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Android Developers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "Android Developers" group. 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