java.lang.NullPointerException on a null object reference. when accessing "kelas" in firebase android studio
49
What is a NullPointerException, and how do I fix it?
64200
Can Java's NullPointerException be changed to report on which variable was null?
58054
When is it OK to catch NullPointerException?
84461
Unable instantiate android.gms.maps.MapFragment
88920
Is using NULL references OK?
149666
Why can't a null-reference exception name the object that has a null reference?
81565
getClass().getResource() always returning null
54938
Cannot invoke method or retrieve property from null object. Object returned by the following call stack is null. \"File\r\n\"
23964
Why does Java have a "NullPointerException" when there are no pointers in Java?
24517
MVC Spring Implementation - error: java.lang.NullPointerException
137441
Root cause for "Entity is not org-accessible" for sharing object?
132398
What is null in Java?
146476
Java: Why aren't NullPointerExceptions called NullReferenceExceptions?
98426
Using org.json in Servlet causes java.lang.ClassNotFoundException: org.json.JSONException
80631
NullPointerException but compiling?
57327
BaseAdapter class wont setAdapter inside Asynctask - Android
139395
com.sun.istack.SAXException2 : Instance ... is substituting "java.lang.Object", but ... is bound to an anonymous type