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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