Firebase android错误“;无法转换类型为“的值”;
此代码在启动时崩溃 E/AndroidRuntime:致命异常:主 进程:com.example.manya.eventspage,PID:2974 com.google.firebase.database.DatabaseException:未能将java.util.HashMap类型的值转换为字符串 位于com.google.android.gms.internal.zzamy.zzcg(未知来源) 位于com.google.android.gms.internal.zzamy.zzb(未知来源) 在com.google.android.gms.internal.zzamy.zza(未知来源) 位于com.google.firebase.database.DataSnapshot.getValue(未知源) 位于com.example.manya.eventspage.Events$1.onDataChange(Events.java:46) 在com.google.android.gms.internal.zzajp.zza(未知来源) 位于com.google.android.gms.internal.zzakp.zzcxi(未知来源) 位于com.google.android.gms.internal.zzaks$1.run(未知来源) 位于android.os.Handler.handleCallback(Handler.java:751) 位于android.os.Handler.dispatchMessage(Handler.java:95) 位于android.os.Looper.loop(Looper.java:154) 位于android.app.ActivityThread.main(ActivityThread.java:6077) 位于java.lang.reflect.Method.invoke(本机方法) 在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)上 位于com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 代码为Firebase android错误“;无法转换类型为“的值”;,android,firebase,firebase-realtime-database,Android,Firebase,Firebase Realtime Database,此代码在启动时崩溃 E/AndroidRuntime:致命异常:主 进程:com.example.manya.eventspage,PID:2974 com.google.firebase.database.DatabaseException:未能将java.util.HashMap类型的值转换为字符串 位于com.google.android.gms.internal.zzamy.zzcg(未知来源) 位于com.google.android.gms.internal.zzamy.zzb(未知
package com.example.manya.eventspage;
import android.app.DatePickerDialog;
import android.app.TimePickerDialog;
import android.content.Context;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import java.text.*;
import java.text.DateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.*;
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 com.google.firebase.database.ValueEventListener;
public class Events extends AppCompatActivity {
private TextView t;
private static ListView l;
private static ArrayAdapter<String> adapter;
final static ArrayList<String> arrayList = new ArrayList<String>();
FirebaseDatabase database=FirebaseDatabase.getInstance();
protected DatabaseReference myRef;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_events);
t = (TextView) findViewById(R.id.textView3);
l = (ListView) findViewById(R.id.list_view);
myRef=database.getReference().child("events");
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String val=dataSnapshot.child("events").getValue(String.class);
arrayList.add(val);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
// Adapter: You need three parameters 'the context, id of the layout (it will be where the data is shown),
// and the array that contains the data
adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_spinner_item, arrayList);
l.setAdapter(adapter);
}
protected void onResume()
{
super.onResume();
Intent in=getIntent();
if(in.hasExtra(Intent.EXTRA_TEXT))
{
String d=in.getStringExtra(Intent.EXTRA_TEXT);
final DatabaseReference postsRef = database.getReference().child("events");
DatabaseReference newPostRef = postsRef.push();
newPostRef.setValue(new event(d));
arrayList.add(d);
// next thing you have to do is check if your adapter has changed
adapter.notifyDataSetChanged();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.add_event) {
Context context=Events.this;
Class destclass=addevent.class;
Intent str=new Intent(context,destclass);
startActivity(str);
return true;
}
return super.onOptionsItemSelected(item);
}
您的代码无法处理以下事实:您在
/events/events
下有一个事件列表。要正确处理此问题,有两种方法:
ValueEventListener
并在子节点上循环ChildEventListener
myRef=database.getReference().child("events/events"); // note the change in path
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot childSnapshot: dataSnapshot.getChildren()) {
String val=childSnapshot.getValue(String.class);
arrayList.add(val);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});
第二种方法告诉Firebase在其SDK中处理列表,并显示每个子级:
myRef=database.getReference().child("events/events"); // note the change in path
myRef.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String previousChildKey) {
String val=dataSnapshot.getValue(String.class);
arrayList.add(val);
}
...
});
请编辑您的问题,以包含JSON数据结构的最小代表性片段(文本形式,请不要截图)。您可以通过单击菜单中的“导出JSON”链接来获得此信息。解决方法如下:
myRef=database.getReference().child("events/events"); // note the change in path
myRef.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String previousChildKey) {
String val=dataSnapshot.getValue(String.class);
arrayList.add(val);
}
...
});