Can't pass null for argument 'pathString' in child()

[nicoe222]

Can't pass null for argument 'pathString' in child()

i've been following your tutorial and i got this error on my firebasemethod.java

any idea? thanks

[thealpha]

His @nicoe222 @mitchtabian Is no longer going to fix this project , I have faced lot of bugs and fixed it , you can say whats your problem I ll give you another solution

[purnendrasingh]

hey @thealpha @nicoe222 i am facing same issue.
User authentication gets successful but writing to database fails after pressing register button on register activity (Lecture 26,Insert new User Data).
it show:-
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.purnendra.insta_clone_app, PID: 17974
java.lang.NullPointerException: Can't pass null for argument 'pathString' in child()
at com.google.firebase.database.DatabaseReference.child(Unknown Source)
at com.google.firebase.database.DataSnapshot.child(Unknown Source)
at com.purnendra.insta_clone_app.Utils.FireBaseMethods.checkIfUserNameExists(FireBaseMethods.java:59)
at com.purnendra.insta_clone_app.Login.RegisterActivity$2$1.onDataChange(RegisterActivity.java:150)
at com.google.firebase.database.zzp.onDataChange(Unknown Source)
at com.google.android.gms.internal.firebase_database.zzfc.zza(Unknown Source)
at com.google.android.gms.internal.firebase_database.zzgx.zzdr(Unknown Source)
at com.google.android.gms.internal.firebase_database.zzhd.run(Unknown Source)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

Problem is at:-
for (DataSnapshot ds:dataSnapshot.child(userID).getChildren())
in Firebasemethod.
from
if (fireBaseMethods.checkIfUserNameExists(userName, dataSnapshot))
RegisterActivity.

It would be great if you could help.