Class java.util.Map has generic type parameters, please use GenericTypeIndicator instead

Question

I am using firebase to retrieve data from database n use

Map<String, String> map = dataSnapshot.getValue(Map.class);

to get values, but it shows error

E/AndroidRuntime: FATAL EXCEPTION: main
                                                                 Process: com.rana.sahaj.myyu, PID: 13179
                                                                 com.google.firebase.database.DatabaseException: Class java.util.Map has generic type parameters, please use GenericTypeIndicator instead
                                                                     at com.google.android.gms.internal.zzaix.zzb(Unknown Source)
                                                                     at com.google.android.gms.internal.zzaix.zza(Unknown Source)
                                                                     at com.google.firebase.database.DataSnapshot.getValue(Unknown Source)
                                                                     at com.rana.sahaj.myyu.profile.Profile$2.onDataChange(Profile.java:158)
                                                                     at com.google.android.gms.internal.zzafp.zza(Unknown Source)
                                                                     at com.google.android.gms.internal.zzagp.zzSu(Unknown Source)
                                                                     at com.google.android.gms.internal.zzags$1.run(Unknown Source)
                                                                     at android.os.Handler.handleCallback(Handler.java:733)
                                                                     at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                     at android.os.Looper.loop(Looper.java:136)
                                                                     at android.app.ActivityThread.main(ActivityThread.java:5052)
                                                                     at java.lang.reflect.Method.invokeNative(Native Method)
                                                                     at java.lang.reflect.Method.invoke(Method.java:515)
                                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
                                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
                                                                     at dalvik.system.NativeStart.main(Native Method)

here's the code

 DatabaseReference profileRef=mFirebaseRef.child(EEmail);
    profileRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

    -->     Map<String, String> map = (Map<String,String>)dataSnapshot.getValue(Map.class);

            name = (TextView)findViewById(R.id.UserInActivity);
            EmailView= (TextView)findViewById(R.id.emailUser);

            PhotoUrl = map.get("picurl");
             emmaill=map.get("userEmail");

            UserNam = map.get("userNAME");

            name.setText(UserNam);
            EmailView.setText(emmaill);


        }

        @Override
        public void onCancelled(DatabaseError firebaseError) {

        }
    });

n there is no problem with key n values in database. used the solution but not working

None of the answers on this page worked. This answer is the only one that worked for me: stackoverflow.com/a/48711195/4833705 — Lance Samaria
– Lance Samaria, Commented May 6, 2023 at 2:33

Shubhank · Accepted Answer · 2016-06-07 20:03:28Z

60

The error points out correctly where you are going wrong

 Map<String, String> map = dataSnapshot.getValue(Map.class);

Map class uses parameter to define the types of Key and Object where as you don't give them and simply use Map.class which fails.

Try the below code - since Key are always string and we can have any type of Object for them

    Map<String, Object> map = (Map<String, Object>) dataSnapshot.getValue();

answered Jun 7, 2016 at 20:03

Shubhank

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4 Comments

Shubhank Over a year ago

can you update your question with the new code you used ?

Shubhank Over a year ago

use getValue() you are still doing getValue(Map.class);

Hesham Yassin Over a year ago

See my correct answer down below. as no solution here worked for me

Sunil Chaudhary Over a year ago

getting this error now java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Map

ishmaelMakitla · Accepted Answer · 2016-06-07 20:21:58Z

34

To introduce the GenericTypeIndicator, you can change this line:

Map<String, String> map = dataSnapshot.getValue(Map.class);

in to this:

GenericTypeIndicator<Map<String, String>> genericTypeIndicator = new GenericTypeIndicator<Map<String, String>>() {};
Map<String, String> map = dataSnapshot.getValue(genericTypeIndicator );

This should work well in your case. Please give it a try and let me know.

edited Jun 7, 2016 at 20:21

answered Jun 7, 2016 at 20:06

ishmaelMakitla

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3 Comments

ishmaelMakitla Over a year ago

Map<String, String> map = (Map<String, Object>) dataSnapshot.getValue(); should have worked. But in any case, I have updated the answer to show how to use GenericTypeIndicator - you can give this one a try - I hope someone can also find this helpful.

RickBoyerDev Over a year ago

Thanks, this worked whereas the accepted answer did not.

Sunil Chaudhary Over a year ago

getting this error now com.google.firebase.database.DatabaseException: Expected a Map while deserializing, but got a class java.lang.Stri

miken32 · Accepted Answer · 2016-08-08 21:29:22Z

14

I had the same problem and solved it by handling the Object instead trying to have Firebase cast it.

Map <String, String> map = (Map)dataSnapshot.getValue();

did it for me.

edited Aug 8, 2016 at 21:29

miken32

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answered Aug 8, 2016 at 21:19

Walter

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1 Comment

Berat Cevik Over a year ago

Worked for me as well. Nice solution!

Hesham Yassin · Accepted Answer · 2018-06-26 02:15:19Z

2

You need to use the getCheldrin as follows

for (DataSnapshot snapshotNode: dataSnapshot.getChildren()) {
    map.put(snapshotNode.getKey(), snapshotNode.getValue(YOUR_CLASS_TYPE.class));
}

Replace the YOUR_CLASS_TYPE with the class type you expecting. notice that this class must have an empty constructor.

answered Jun 26, 2018 at 2:15

Hesham Yassin

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Comments

Romário Gabaritado · Accepted Answer · 2020-08-03 23:44:02Z

0

Chage

Map<String, String> map = (Map<String,String>)dataSnapshot.getValue(Map.class);

by this

Map map = (Map) dataSnapshot.getValue(Map.class);

answered Aug 3, 2020 at 23:44

Romário Gabaritado

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1 Comment

Simon.S.A. Over a year ago

This answer duplicates content from an existing highly rated answer. Please ensure your answers add something more to the post. See How to Answer for more guidance.

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