类java.util.Map具有泛型类型参数,请改用GenericTypeIndicator

Question

我正在使用firebase从数据库中检索数据

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

获取值,但它显示错误

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)

这是代码

 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数据库中的键n值没有问题.使用了解决方案,但没有工作

Answer 1

错误指出您出错的地方

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

Map类使用参数来定义Key和Object的类型,而不提供它们,只需使用Map.class哪个失败.

尝试下面的代码 - 因为Key总是字符串,我们可以为它们提供任何类型的Object

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

Answer 2

要介绍GenericTypeIndicator,你可以改变这一行:

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

对此:

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

这应该适用于您的情况.请试试看,让我知道.

Answer 3

我有同样的问题,并通过处理Object而不是尝试让Firebase投射它来解决它.

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

为我做了