Java.util.ConcurrentModificationException and SharedPreference

Question

I found this crash in crash logs. I do not know when this happens. Can someone give me some advice, what is the reason? Perhaps someone has the same accident.

java.util.ConcurrentModificationException at java.util.HashMap$HashIterator.nextEntry(HashMap.java:787) at java.util.HashMap$KeyIterator.next(HashMap.java:814) at com.android.internal.util.XmlUtils.writeSetXml(XmlUtils.java:350) at com.android.internal.util.XmlUtils.writeValueXml(XmlUtils.java:688) at com.android.internal.util.XmlUtils.writeMapXml(XmlUtils.java:295) at com.android.internal.util.XmlUtils.writeMapXml(XmlUtils.java:264) at com.android.internal.util.XmlUtils.writeMapXml(XmlUtils.java:230) at com.android.internal.util.XmlUtils.writeMapXml(XmlUtils.java:187) at android.app.SharedPreferencesImpl.writeToFile(SharedPreferencesImpl.java:597) at android.app.SharedPreferencesImpl.access$800(SharedPreferencesImpl.java:51) at android.app.SharedPreferencesImpl$2.run(SharedPreferencesImpl.java:512) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) at java.lang.Thread.run(Thread.java:818) 

Answer 1

We saw this exception when using the SharedPreferences getStringSet method. This method returns a collection that should not be modified . Changing this set while the SharedPreferences object is serialized for flash will throw a ConcurrentModificationException.

This will also happen if you use getAll and change the returned map.

See documentation

Answer 2

Someone already answered this question, you might be interested to take a look: ConcurrentModificationException in Android when accessing the general settings