嘗試從Firebase獲取數據時Android應用程序崩潰

Question

我正在開發一個Android應用，並將Firebase集成到其中。 連接成功，並且寫入Firebase沒問題，當應用程序嘗試接收要顯示在應用程序中的數據時，應用程序崩潰。 如果有人可以幫助，我已在下面添加了我的代碼。

Capture_Meetings.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.firebase.client.DataSnapshot;
import com.firebase.client.Firebase;
import com.firebase.client.FirebaseError;
import com.firebase.client.ValueEventListener;

public class Capture_Meetings extends AppCompatActivity {

private EditText editTextName;
private EditText editTextAddress;
private EditText editDateTime;
private TextView textViewPersons;
private Button buttonSave;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_capture__meetings);

    Firebase.setAndroidContext(this);

    buttonSave = (Button) findViewById(R.id.buttonSave);
    editTextName = (EditText) findViewById(R.id.editTextName);
    editTextAddress = (EditText) findViewById(R.id.editTextAddress);
    editDateTime = (EditText) findViewById(R.id.editDateTime);

    textViewPersons = (TextView) findViewById(R.id.textViewPersons);

    buttonSave.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //Creating firebase object
            Firebase ref = new Firebase(Config.FIREBASE_URL);

            //Getting values to store
            String name = editTextName.getText().toString().trim();
            String address = editTextAddress.getText().toString().trim();
            String DateTime = editDateTime.getText().toString().trim();

            //Creating Person object
            final MeetingUser person = new MeetingUser();

            //Adding values
            person.setName(name);
            person.setAddress(address);
            person.setDateTime(DateTime);

            //Storing values to firebase
            ref.child("Person").push().setValue(person);


            //Value event listener for realtime data update
            ref.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot snapshot)
                {
                    for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                        //Getting the data from snapshot
                        MeetingUser person = postSnapshot.getValue(MeetingUser.class);

                        //Adding it to a string
                        String string = "\n Name of School: "+person.getName()+"\n Date and Time:"+ person.getDateTime()+"\nMeeting Notes: "+person.getAddress()+"\n\n";

                        //Displaying it on textview
                        textViewPersons.setText(string);
                    }
                }

                @Override
                public void onCancelled(FirebaseError firebaseError) {
                    System.out.println("The read failed: " + firebaseError.getMessage());
                }
            });

        }
    });
}
}

MeetingUser.java構造函數

public class MeetingUser {
//name and address string
private String Key;
private String name;
private String address;
private String DateTime;

public MeetingUser() {
  /*Blank default constructor essential for Firebase*/
}
//Getters and setters
public String getKey ()
{
    return Key;
}

public void setKey (String Key)
{
    this.Key = Key;
}
public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getAddress() {
    return address;
}

public void setAddress(String address) {
    this.address = address;
}

public String getDateTime()
{
    return DateTime;
}

public void setDateTime (String DateTime)
{
    this.DateTime = DateTime;
}
}

崩潰日志：

com.firebase.client.FirebaseException: Failed to bounce to type
                      at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:185)
                      at com.example.pooveshin.saica_sgb.Capture_Meetings$1$1.onDataChange(Capture_Meetings.java:67)
                      at com.firebase.client.core.ValueEventRegistration.fireEvent(ValueEventRegistration.java:45)
                      at com.firebase.client.core.view.DataEvent.fire(DataEvent.java:45)
                      at com.firebase.client.core.view.EventRaiser$1.run(EventRaiser.java:38)
                      at android.os.Handler.handleCallback(Handler.java:739)
                      at android.os.Handler.dispatchMessage(Handler.java:95)
                      at android.os.Looper.loop(Looper.java:135)
                      at android.app.ActivityThread.main(ActivityThread.java:5254)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at java.lang.reflect.Method.invoke(Method.java:372)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
                   Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "-KVZjE7GFxVENXAnemZF" (class com.example.pooveshin.saica_sgb.MeetingUser), not marked as ignorable (4 known properties: , "name", "dateTime", "address", "key"])
                      at [Source: java.io.StringReader@20f5d5e1; line: 1, column: 26] (through reference chain: com.example.pooveshin.saica_sgb.MeetingUser["-KVZjE7GFxVENXAnemZF"])
                      at com.fasterxml.jackson.databind.DeserializationContext.reportUnknownProperty(DeserializationContext.java:555)
                      at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:708)
                      at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:1160)
                      at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:315)
                      at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
                      at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
                      at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2034)
                      at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:183)
                      at com.example.pooveshin.saica_sgb.Capture_Meetings$1$1.onDataChange(Capture_Meetings.java:67) 
                      at com.firebase.client.core.ValueEventRegistration.fireEvent(ValueEventRegistration.java:45) 
                      at com.firebase.client.core.view.DataEvent.fire(DataEvent.java:45) 
                      at com.firebase.client.core.view.EventRaiser$1.run(EventRaiser.java:38) 
                      at android.os.Handler.handleCallback(Handler.java:739) 
                      at android.os.Handler.dispatchMessage(Handler.java:95) 
                      at android.os.Looper.loop(Looper.java:135) 
                      at android.app.ActivityThread.main(ActivityThread.java:5254) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:372) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 

Answer 1

看看這個：

public void setKey (String Key)
{
    this.Key = Key;
}

反序列化后， Jackson會假定該字段為key但是您將其寫為Key ，因此無法將其映射到對象的字段。

將private String Key更改為private String key ，與DateTime相同，如果可能，請使用小寫字段。