Hey guys.
This is not an Android issue per-se, but I am puzzled about a Java issue and
want to pick your brains.
I recently got a couple of bug reports with a NPE that I don't understand
and can't reproduce myself. Here is an abbreviated representation of the
offending class. I tried to stay as close to the actual code as possible.
public class EntryManager {
private static EntryManager instance;
private Map<DBQuery, Boolean> isMarkAllReadPossibleCache;
private EntryManager(Context ctx) {
..
isMarkAllReadPossibleCache = new HashMap<DBQuery, Boolean>();
..
}
public static synchronized EntryManager getInstance(final Context context)
{
if (instance == null)
instance = new EntryManager(context.getApplicationContext());
return instance;
}
void fireModelUpdated(final String atomId) {
..
isMarkAllReadPossibleCache.clear();
..
}
public boolean isMarkAllReadPossible(final DBQuery dbq) {
if (!isMarkAllReadPossibleCache.containsKey(dbq))
isMarkAllReadPossibleCache.put(dbq,
databaseHelper.isMarkAllReadPossible(dbq));
return isMarkAllReadPossibleCache.get(dbq); <!-- NPE is raised here
}
..
}
In the last line from above a NPE is thrown. So the instance variable
isMarkAllReadPossibleCache must be null, right? But I don't see where this
could happen. It's initialized in the constructor and never set to null
afterwards.
For completeness here is a stack trace:
java.lang.NullPointerException
at com.newsrob.EntryManager.isMarkAllReadPossible(EntryManager.java:1529)
at
com.newsrob.activities.AbstractNewsRobListActivity.shouldMarkAllReadButtonBeEnabled(AbstractNewsRobListActivity.java:327)
at
com.newsrob.activities.AbstractNewsRobListActivity.updateButtons(AbstractNewsRobListActivity.java:236)
at
com.newsrob.activities.AbstractNewsRobListActivity.access$2(AbstractNewsRobListActivity.java:215)
<-- removed the private access modifier meanwhile
at
com.newsrob.activities.AbstractNewsRobListActivity$13.run(AbstractNewsRobListActivity.java:626)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4203)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
at dalvik.system.NativeStart.main(Native Method)
Any ideas?
Cheers,
Mariano
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