NickName:YaraR Ask DateTime:2017-03-25T18:51:20

Android Studio - Retrieving data from firebase is not working

I'm working on retrieving some data from Firebase and i followed some Youtube tutorials that were working fine,

but out of nowhere the retrieving is not working anymore,

the path that i'm setting is correct but i get an empty list even though there is data from where i am retrieving.

private ListView mListView;
private ArrayList<String> mHospitalNames= new ArrayList<>();
private Firebase mRefRoot;

this is the path:

mRefRoot=new Firebase("https://prototype-d2a84.firebaseio.com/Search/"+countryName+"/"+mCity+"/"+bloodType);

this is the code that i am using:

   mListView = (ListView) findViewById(R.id.listview);

    final ArrayAdapter<String> mArrayAdapter= new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mHospitalNames);

    mListView.setAdapter(mArrayAdapter);

    mRefRoot.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {

            String value = dataSnapshot.getValue(String.class);
            mHospitalNames.add(value);
            mArrayAdapter.notifyDataSetChanged();
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    });

this is how my database looks like

can someone tell me whats wrong?

Copyright Notice：Content Author:「YaraR」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/43015468/android-studio-retrieving-data-from-firebase-is-not-working

Answers

ColdSpike 2017-03-25T11:23:52

Check if the rules in your database are set to true if you are not using authentication\n\n{\n \"rules\": {\n \".read\": \"true\",\n \".write\": \"true\"\n }\n}\n\n\nif that is not the problem then check what your datasnapshot is returning.If your database is something like this\n\nroot\n -country\n -city\n -bloodgroup\n -B+\n -123:something\n -111:something\n\n\nthen you have to give the key for which you want to get the value. example\n\ndatasnapshot.child(\"B+\").child(\"123\").getValue();//for first child i.e 123\ndatasnapshot.child(\"B+\").child(\"111\").getValue();//for second child i.e 111\n\nelse if you want the entire set of values then, you can use the above line multiple times with different key or use a class to get all the values at once.\n\nAs per your database you have keys as numbers,i would suggest to change that and keep strings as this would cause problem in retrieving data if you use a class.\n\nclass mClass{\n private String first;\n private String second;\n mClass(){}\n mClass(String first,String second){\n this.first=first;\n this.second=second;\n }\n public String getFirst(){\n return this.first;\n }\n public String getSecond(){\n return this.second;\n }\n}\n\n\nNow you can get the data in this class.\n\nmClass mclass = datasnapshot.getValue(mClass.class);\n\n\nNow where you want to use this data just call the getter function.\n\ntext.setText(mclass.getFirst());\n",