从Firebase android获取特定数据
我一直在尝试从Firebase获取数据。这是数据库结构：
下面的数据库快照
我想只检索PartyName和ID。我的代码是这样的：
listView = (ListView) findViewById(R.id.listView);
Firebase.setAndroidContext(this);
firebase = new Firebase("https://login-b3a11.firebaseio.com/Users");
// com.firebase.client.Query query=firebase.orderByChild("Date").equalTo("ID");
listView = (ListView) findViewById(R.id.listView);
final ArrayAdapter arrayAdapter = new ArrayAdapter(Status.this, android.R.layout.simple_list_item_1, listGet);
listView.setAdapter(arrayAdapter);
firebase.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
for(DataSnapshot ds:dataSnapshot.getChildren()){
Get g= (Get) ds.getValue();
listGet.add(g.getPartyName());
arrayAdapter.notifyDataSetChanged();
}
}
和Get是一个具有getter和setter方法的类。但是我的应用程序崩溃了。
logcat的
12-24 13:40:11.010 2134-3707/? E/ConnectivityService: RemoteException caught trying to send a callback msg for NetworkRequest [ id=490, legacyType=-1, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED] ]
12-24 13:40:11.132 2134-3707/? E/ConnectivityService: RemoteException caught trying to send a callback msg for NetworkRequest [ id=491, legacyType=-1, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED] ]
12-24 13:40:11.330 20641-20641/? E/FirebaseApp: Firebase API initialization failure.
java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at com.google.firebase.FirebaseApp.zza(Unknown Source)
at com.google.firebase.FirebaseApp.initializeApp(Unknown Source)
at com.google.firebase.FirebaseApp.initializeApp(Unknown Source)
at com.google.firebase.FirebaseApp.zzeh(Unknown Source)
at com.google.firebase.provider.FirebaseInitProvider.onCreate(Unknown Source)
at android.content.ContentProvider.attachInfo(ContentProvider.java:1748)
at android.content.ContentProvider.attachInfo(ContentProvider.java:1723)
at com.google.firebase.provider.FirebaseInitProvider.attachInfo(Unknown Source)
at android.app.ActivityThread.installProvider(ActivityThread.java:5174)
at android.app.ActivityThread.installContentProviders(ActivityThread.java:4769)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4709)
at android.app.ActivityThread.-wrap1(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1415)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
Caused by: java.lang.NoSuchMethodError: No static method zzz(Ljava/lang/Object;)Ljava/lang/Object; in class Lcom/google/android/gms/common/internal/zzaa; or its super classes (declaration of 'com.google.android.gms.common.internal.zzaa' appears in /data/app/com.example.amisha.login-2/base.apk)
at com.google.android.gms.measurement.internal.zzx.zzbd(Unknown Source)
at com.google.android.gms.measurement.AppMeasurement.getInstance(Unknown Source)
at java.lang.reflect.Method.invoke(Native Method)
at com.google.firebase.FirebaseApp.zza(Unknown Source)
at com.google.firebase.FirebaseApp.initializeApp(Unknown Source)
at com.google.firebase.FirebaseApp.initializeApp(Unknown Source)
at com.google.firebase.FirebaseApp.zzeh(Unknown Source)
at com.google.firebase.provider.FirebaseInitProvider.onCreate(Unknown Source)
at android.content.ContentProvider.attachInfo(ContentProvider.java:1748)
at android.content.ContentProvider.attachInfo(ContentProvider.java:1723)
at com.google.firebase.provider.FirebaseInitProvider.attachInfo(Unknown Source)
at android.app.ActivityThread.installProvider(ActivityThread.java:5174)
at android.app.ActivityThread.installContentProviders(ActivityThread.java:4769)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4709)
at android.app.ActivityThread.-wrap1(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1415)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
12-24 13:40:11.513 20672-20672/? E/NEW_BHD: Battery Power
5 个答案:
答案 0 :(得分：0)
本教程将帮助您掌握新的实施方式 http://www.androidhive.info/2016/10/android-working-with-firebase-realtime-database/ https://firebase.google.com/docs/database/android/start/
答案 1 :(得分：0)
首先，您必须以正确的方式引用您的数据库。从代码中删除这两行：
Firebase.setAndroidContext(this);
firebase = new Firebase("https://login-b3a11.firebaseio.com/Users");
// com.firebase.client.Query
用这个替换它们
FirebaseDatbase mFirebaseDatabase = FirebaseDatabase.getInstance();
DatabaseReference mMessagesDatabaseReference=mFirebaseDatabase.getReference();
现在，您可以使用名为DatabaseReference的{{1}}对象发送您的查询。
答案 2 :(得分：0)
FATAL EXCEPTION: main
Process: com.example.amisha.login, PID: 4849
java.lang.ClassCastException: java.lang.String cannot be cast to com.example.amisha.login.Get
at com.example.amisha.login.Status$1.onChildAdded(Status.java:52)
at com.google.android.gms.internal.zzahh.zza(Unknown Source)
at com.google.android.gms.internal.zzajh.zzctc(Unknown Source)
at com.google.android.gms.internal.zzajk$1.run(Unknown Source)
at android.os.Handler.handleCallback(Handler.java:746)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
12-24 16:05:25.710 5445-5445/? E/NEW_BHD: Battery Power Supply logging Daemon start!!!!!
12-24 16:05:25.711 5445-5445/? E/NEW_BHD: Cannot run on production devices!
12-24 16:05:30.734 5463-5463/? E/NEW_BHD: Battery Power Supply logging Daemon start!!!!!
12-24 16:05:30.735 5463-5463/? E/NEW_BHD: Cannot run on production devices!
12-24 16:05:35.752 5464-5464/? E/NEW_BHD: Battery Power Supply logging Daemon start!!!!!
12-24 16:05:35.753 5464-5464/? E/NEW_BHD: Cannot run on production devices!
12-24 16:05:36.425 2134-3707/? E/ConnectivityService: RemoteException caught trying to send a callback msg for NetworkRequest [ id=512, legacyType=-1, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED] ]
12-24 16:05:37.045 5489-5489/? E/Finsky: [1] com.google.android.finsky.wear.bl.a(847): onConnectionFailed: ConnectionResult{statusCode=API_UNAVAILABLE, resolution=null, message=null}
12-24 16:05:37.351 2134-4459/? E/LocSvc_IzatApiV02: E/virtual int izat_core::IzatApiV02::getBatchSize(int32_t):620]: Error : st = 4, ind.status = -1600126925
12-24 16:05:37.351 2134-4459/? E/LocSvc_IzatApiV02: E/virtual int izat_core::IzatApiV02::getBatchSize(int32_t):633]: get batching size failed.Or modem does not support batching
12-24 16:05:37.507 2134-3707/? E/ConnectivityService: RemoteException caught trying to send a callback msg for NetworkRequest [ id=514, legacyType=-1, [ Capabilities: INTERNET&NOT_
我现在得到了这个。尝试的代码是：
listView = (ListView) findViewById(R.id.listView);
FirebaseDatabase.getInstance().setPersistenceEnabled(true);
mDatabase=FirebaseDatabase.getInstance().getReferenceFromUrl("https://login-b3a11.firebaseio.com/Users");
listView = (ListView) findViewById(R.id.listView);
final ArrayAdapter arrayAdapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1, listGet);
listView.setAdapter(arrayAdapter);
mDatabase.addChildEventListener(new com.google.firebase.database.ChildEventListener() {
@Override
public void onChildAdded(com.google.firebase.database.DataSnapshot dataSnapshot, String s) {
for(com.google.firebase.database.DataSnapshot ds:dataSnapshot.getChildren()){
Get g=new Get();
g=(Get)ds.getValue();
myadapter.add(g.getPartyName());
arrayAdapter.notifyDataSetChanged();
}
}
答案 3 :(得分：0)
问题是你是以错误的方式投射它。在onChildAdded中执行此操作
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
for(DataSnapshot ds:dataSnapshot.getChildren()){
Get g= ds.getValue(Get.class);
listGet.add(g.getPartyName());
arrayAdapter.notifyDataSetChanged();
}
}
答案 4 :(得分：0)
FirebaseDatabase database ;
instanse在onCreate上创建
database = FirebaseDatabase.getInstance();
DatabaseReference dbOrderReference = database.getReference("Users/" +"001");
dbOrderReference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(final DataSnapshot dataSnapshot) {
//get id and phone_number
String id=String.valueOf(dataSnapshot.child("id").getValue());
String phone_num=String.valueOf(dataSnapshot.child("PhoneNo").getValue());
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
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