Application Crash when attempting to get child from Firebase - firebase

Question

MY application is crashing on line 43:
float value = dataSnapshot.child("temp").getValue(float.class);
When i remove the .child from the addChildEventListener and from the Datasnapshot , the app will display the float value from the database.
My aim is to display both a float value and then add in another line to display the Humidity value my database will hold.
so i will be attempting .child("temp").child("humi") to be displayed on a listview.
Can anybody steer me in the right direction or help me resolve why i cant specify child entries.
ListView listview = (ListView) findViewById(R.id.listview);
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1, list);
listview.setAdapter(adapter);
//INITIALIZE FIREBASE DB
db = FirebaseDatabase.getInstance().getReference();
db.child("temp").limitToLast(1).addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
float value = dataSnapshot.child("temp").getValue(float.class);
list.add("System Temperture: " + value);
adapter.notifyDataSetChanged();
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
adapter.clear();
float value = dataSnapshot.child("temp").getValue(float.class);
list.add("System Temperture: " + value);
adapter.notifyDataSetChanged();
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
JSON value from firebase
{
"humi" : {
"-KaxKLD00Ib97d1dRbvR" : 17.0
},
"temp" : {
"-KaxKL8G17y4ezfdBMDP" : 21.0
}
}
Logcat
01-20 18:32:18.675 16935-16935/com.m.j.project.josephmay E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.m.j.project.josephmay, PID: 16935
java.lang.NullPointerException: Attempt to invoke virtual method 'float java.lang.Float.floatValue()' on a null object reference
at com.m.j.project.josephmay.MainActivity$1.onChildAdded(MainActivity.java:43)
at com.google.android.gms.internal.zzblz.zza(Unknown Source)
at com.google.android.gms.internal.zzbnz.zzYj(Unknown Source)
at com.google.android.gms.internal.zzboc$1.run(Unknown Source)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
01-20 18:32:26.645 16935-17099/com.m.j.project.josephmay W/DynamiteModule: Local module descriptor class for com.google.firebase.auth not found.
01-20 18:32:26.645 16935-17099/com.m.j.project.josephmay W/ResourcesManager: getTopLevelResources: /data/app/com.google.android.gms-1/base.apk / 1.0 running in com.m.j.project.josephmay rsrc of package com.google.android.gms

Answer 1

I think I was running into a similar issue and this response from Frank helped me: https://groups.google.com/forum/#!topic/firebase-talk/-cdTDFBOmMw.
When you are creating the new record within Firebase, are you doing setValue() for "humi" and "temp" separately or doing setValue() for the entire object? Try switching it to setValue() for the whole object.