我在 firebase 数据库中有一些数据，我正尝试从 Android 应用程序中检索这些数据，但它无法正常工作。我写的代码是:
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import java.util.ArrayList;
public class NodeList extends AppCompatActivity {
ArrayList<String> mNames = new ArrayList<>();
ListView mListView;
DatabaseReference myRef;
ArrayAdapter<String> arrayAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_node_list);
mListView = (ListView)findViewById(R.id.listView);
myRef = FirebaseDatabase.getInstance().getReference();
arrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, mNames);
mListView.setAdapter(arrayAdapter);
myRef.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
String value = dataSnapshot.getValue(String.class);
}
@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(DatabaseError databaseError) {
}
});
}
}
应用程序在我打开时崩溃了。我不明白我哪里错了。这是我的数据库的结构: Database structure
关于如何检索数据和显示数据的任何想法？
提前致谢!
日志:
10-10 16:54:06.651 10672-10672/? I/art: Late-enabling -Xcheck:jni
10-10 16:54:07.117 10672-10672/com.mohana.pdc W/System: ClassLoader referenced unknown path: /data/app/com.mohana.pdc-2/lib/arm
10-10 16:54:07.187 10672-10704/com.mohana.pdc W/DynamiteModule: Local module descriptor class for com.google.firebase.auth not found.
10-10 16:54:07.193 10672-10707/com.mohana.pdc I/DynamiteModule: Considering local module com.google.android.gms.flags:2 and remote module com.google.android.gms.flags:0
10-10 16:54:07.193 10672-10707/com.mohana.pdc I/DynamiteModule: Selected local version of com.google.android.gms.flags
10-10 16:54:07.196 10672-10707/com.mohana.pdc W/System: ClassLoader referenced unknown path:
10-10 16:54:07.197 10672-10704/com.mohana.pdc W/DynamiteModule: Local module descriptor class for com.google.firebase.auth not found.
10-10 16:54:07.205 10672-10707/com.mohana.pdc W/DynamiteModule: Local module descriptor class for com.google.android.gms.crash not found.
10-10 16:54:07.208 10672-10707/com.mohana.pdc I/DynamiteModule: Considering local module com.google.android.gms.crash:0 and remote module com.google.android.gms.crash:7
10-10 16:54:07.209 10672-10707/com.mohana.pdc I/DynamiteModule: Selected remote version of com.google.android.gms.crash, version >= 7
10-10 16:54:07.221 10672-10707/com.mohana.pdc W/System: ClassLoader referenced unknown path: /data/user_de/0/com.google.android.gms/app_chimera/m/00000023/n/armeabi-v7a
10-10 16:54:07.221 10672-10707/com.mohana.pdc W/System: ClassLoader referenced unknown path: /data/user_de/0/com.google.android.gms/app_chimera/m/00000023/n/armeabi
10-10 16:54:07.229 10672-10707/com.mohana.pdc I/FirebaseCrashApiImpl: FirebaseCrashApiImpl created by ClassLoader t[DexPathList[[zip file "/data/user_de/0/com.google.android.gms/app_chimera/m/00000023/DynamiteModulesC_GmsCore_prodmnc_xxhdpi_release.apk"],nativeLibraryDirectories=[/data/user_de/0/com.google.android.gms/app_chimera/m/00000023/n/armeabi-v7a, /data/user_de/0/com.google.android.gms/app_chimera/m/00000023/n/armeabi, /system/lib, /vendor/lib]]]
10-10 16:54:07.229 10672-10707/com.mohana.pdc I/FirebaseCrash: FirebaseCrash reporting loaded - com.google.android.gms.internal.zzdmw@afc9448
10-10 16:54:07.232 10672-10672/com.mohana.pdc I/FA: App measurement is starting up, version: 11400
10-10 16:54:07.232 10672-10672/com.mohana.pdc I/FA: To enable debug logging run: adb shell setprop log.tag.FA VERBOSE
10-10 16:54:07.240 10672-10708/com.mohana.pdc I/DynamiteModule: Considering local module com.google.android.gms.flags:2 and remote module com.google.android.gms.flags:0
10-10 16:54:07.240 10672-10708/com.mohana.pdc I/DynamiteModule: Selected local version of com.google.android.gms.flags
10-10 16:54:07.246 10672-10708/com.mohana.pdc W/DynamiteModule: Local module descriptor class for com.google.android.gms.crash not found.
10-10 16:54:07.251 10672-10672/com.mohana.pdc I/FA: To enable faster debug mode event logging run:
adb shell setprop debug.firebase.analytics.app com.mohana.pdc
10-10 16:54:07.251 10672-10672/com.mohana.pdc D/FA: Debug-level message logging enabled
10-10 16:54:07.261 10672-10708/com.mohana.pdc I/FirebaseCrashApiImpl: FirebaseCrash reporting API initialized
10-10 16:54:07.289 10672-10672/com.mohana.pdc I/FirebaseInitProvider: FirebaseApp initialization successful
10-10 16:54:07.290 10672-10672/com.mohana.pdc I/InstantRun: starting instant run server: is main process
10-10 16:54:07.290 10672-10708/com.mohana.pdc I/FirebaseCrash: FirebaseCrash reporting initialized com.google.android.gms.internal.zzdmw@afc9448
10-10 16:54:07.291 10672-10708/com.mohana.pdc D/FirebaseCrash: Firebase Analytics Listener for Firebase Crash is initialized
10-10 16:54:07.309 10672-10712/com.mohana.pdc D/FA: Connected to remote service
10-10 16:54:17.153 10672-10857/com.mohana.pdc I/FirebaseCrash: Sending crashes
10-10 16:54:17.354 10672-10704/com.mohana.pdc W/DynamiteModule: Local module descriptor class for com.google.firebase.auth not found.
最佳答案
您需要像这样在此处提供完整路径引用:
myRef = FirebaseDatabase.getInstance().getReference("Users").child("User1");
关于android - android 中的 firebase 数据检索错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46665443/