Я пытаюсь написать приложение Firebase на Android, которое, по сути, представляет собой один большой чат в реальном времени. У меня работают функции входа и выхода, но когда я пытаюсь получить экземпляры своего класса сообщений из БД, я получаю странную ошибку о проблеме преобразования его в строку, которая вызывает сбой приложения. Должен быть какой-то скрытый звонок, о котором я не знаю.

Я сузил свою проблему до этой части моей основной деятельности:

private void displayChatMessages() {
        ListView listOfMessages = (ListView)findViewById(R.id.list_of_messages);

        adapter = new FirebaseListAdapter<ChatMessage>(this, ChatMessage.class,
                R.layout.message, FirebaseDatabase.getInstance().getReference()) {
            @Override
            protected void populateView(View v, ChatMessage model, int position) {
                // Get references to the views of message.xml
                TextView messageText = (TextView)v.findViewById(R.id.message_text);
                TextView messageUser = (TextView)v.findViewById(R.id.message_user);
                TextView messageTime = (TextView)v.findViewById(R.id.message_time);

                // Set their text
                messageText.setText(model.getMessageText());
                messageUser.setText(model.getMessageUser());

                // Format the date before showing it
                messageTime.setText(DateFormat.format("dd-MM-yyyy (HH:mm:ss)",
                        model.getMessageTime()));
            }
        };

        listOfMessages.setAdapter(adapter);
    }

Я предполагаю, что это как-то связано с моим вызовом populateView, хотя я понятия не имею, почему.

Вот ошибка согласно моему журналу-кошке:

om.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type foo.bar.ChatMessage
                                                               at com.google.android.gms.internal.zg.zzb(Unknown Source:870)
                                                               at com.google.android.gms.internal.zg.zza(Unknown Source:0)
                                                               at com.google.firebase.database.DataSnapshot.getValue(Unknown Source:10)
                                                               at com.firebase.ui.database.FirebaseListAdapter.parseSnapshot(FirebaseListAdapter.java:127)
                                                               at com.firebase.ui.database.FirebaseListAdapter.getItem(FirebaseListAdapter.java:116)
                                                               at com.firebase.ui.database.FirebaseListAdapter.getView(FirebaseListAdapter.java:146)
                                                               at android.widget.AbsListView.obtainView(AbsListView.java:2408)
                                                               at android.widget.ListView.makeAndAddView(ListView.java:2052)
                                                               at android.widget.ListView.fillDown(ListView.java:786)
                                                               at android.widget.ListView.fillFromTop(ListView.java:847)
                                                               at android.widget.ListView.layoutChildren(ListView.java:1798)
                                                               at android.widget.AbsListView.onLayout(AbsListView.java:2207)
                                                               at android.view.View.layout(View.java:19653)
                                                               at android.view.ViewGroup.layout(ViewGroup.java:6082)
                                                               at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1080)
                                                               at android.view.View.layout(View.java:19653)
                                                               at android.view.ViewGroup.layout(ViewGroup.java:6082)
                                                               at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                                                               at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                                                               at android.view.View.layout(View.java:19653)
                                                               at android.view.ViewGroup.layout(ViewGroup.java:6082)
                                                               at android.support.v7.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:443)
                                                               at android.view.View.layout(View.java:19653)
                                                               at android.view.ViewGroup.layout(ViewGroup.java:6082)
                                                               at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                                                               at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                                                               at android.view.View.layout(View.java:19653)
                                                               at android.view.ViewGroup.layout(ViewGroup.java:6082)
                                                               at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
                                                               at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
                                                               at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
                                                               at android.view.View.layout(View.java:19653)
                                                               at android.view.ViewGroup.layout(ViewGroup.java:6082)
                                                               at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                                                               at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                                                               at com.android.internal.policy.DecorView.onLayout(DecorView.java:758)
                                                               at android.view.View.layout(View.java:19653)
                                                               at android.view.ViewGroup.layout(ViewGroup.java:6082)
                                                               at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2626)
                                                               at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2321)
                                                               at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1466)
                                                               at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6982)
                                                               at android.view.Choreographer$CallbackRecord.run(Choreographer.java:927)
                                                               at android.view.Choreographer.doCallbacks(Choreographer.java:729)
                                                               at android.view.Choreographer.doFrame(Choreographer.java:658)
                                                               at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:913)
                                                               at android.os.Handler.handleCallback(Handler.java:789)
                                                               at android.os.Handler.dispatchMessage(Handler.java:98)
                                                               at android.os.Looper.loop(Looper.java:180)
                                                               at android.app.ActivityThread.main(ActivityThread.java:6950)
                                                               at java.lang.reflect.Method.invoke(Native Method)
                                                               at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:835)

Вот моя основная деятельность

package foo.bar;

import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.firebase.ui.auth.AuthUI;
import com.firebase.ui.database.FirebaseListAdapter;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.FirebaseDatabase;


public class MainActivity extends AppCompatActivity {

    private FirebaseAuth mAuth; // object used to authorize the app to connect to Firebase
    private FirebaseListAdapter<ChatMessage> adapter;

    int SIGN_IN_REQUEST_CODE = 1;

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

        int SIGN_IN_REQUEST_CODE = 1;

        //Start the user sign-in display if the user is not logged in.
        if(FirebaseAuth.getInstance().getCurrentUser() == null) {
            // Start sign in/sign up activity
            startActivityForResult(
                    AuthUI.getInstance()
                            .createSignInIntentBuilder()
                            .build(),
                    SIGN_IN_REQUEST_CODE
            );
        } else {
            // User is already signed in. Therefore, display
            // a welcome Toast
            Toast.makeText(this,
                    "Welcome " + FirebaseAuth.getInstance()
                            .getCurrentUser()
                            .getDisplayName(),
                    Toast.LENGTH_LONG)
                    .show();

            // Load chat room contents
            displayChatMessages();
        }

        //Attach a listener to the FAB so that users can send messages using it.
        FloatingActionButton fab = (FloatingActionButton)findViewById(R.id.fab);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                EditText input = (EditText)findViewById(R.id.input);

                // Read the input field and push a new instance
                // of ChatMessage to the Firebase database
                FirebaseDatabase.getInstance()
                        .getReference()
                        .push()
                        .setValue(new ChatMessage(input.getText().toString(),
                                FirebaseAuth.getInstance()
                                        .getCurrentUser()
                                        .getDisplayName())
                        );

                // Clear the input
                input.setText("");
            }
        }); //end of FAB listener

    } //end of onCreate

    private void displayChatMessages() {
        ListView listOfMessages = (ListView)findViewById(R.id.list_of_messages);

        adapter = new FirebaseListAdapter<ChatMessage>(this, ChatMessage.class,
                R.layout.message, FirebaseDatabase.getInstance().getReference()) {
            @Override
            protected void populateView(View v, ChatMessage model, int position) {
                // Get references to the views of message.xml
                TextView messageText = (TextView)v.findViewById(R.id.message_text);
                TextView messageUser = (TextView)v.findViewById(R.id.message_user);
                TextView messageTime = (TextView)v.findViewById(R.id.message_time);

                // Set their text
                messageText.setText(model.getMessageText());
                messageUser.setText(model.getMessageUser());

                // Format the date before showing it
                messageTime.setText(DateFormat.format("dd-MM-yyyy (HH:mm:ss)",
                        model.getMessageTime()));
            }
        };

        listOfMessages.setAdapter(adapter);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode,
                                    Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == SIGN_IN_REQUEST_CODE) {
            if(resultCode == RESULT_OK) {
                Toast.makeText(this,
                        "Successfully signed in. Welcome!",
                        Toast.LENGTH_LONG)
                        .show();
                displayChatMessages();
            } else {
                Toast.makeText(this,
                        "We couldn't sign you in. Please try again later.",
                        Toast.LENGTH_LONG)
                        .show();

                // Close the app
                finish();
            }
        }

    }

    //Configure and implement the side menu
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu, menu);
        return true;
    }

    //Sign out activity function
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(item.getItemId() == R.id.menu_sign_out) {//if the sign-out option is selected from the menu

            //Sign the user out
            AuthUI.getInstance().signOut(this)
                    .addOnCompleteListener(new OnCompleteListener<Void>() {
                        @Override
                        public void onComplete(@NonNull Task<Void> task) {
                            Toast.makeText(MainActivity.this,
                                    "You have been signed out.",
                                    Toast.LENGTH_LONG)
                                    .show();

                            // Close activity
                            finish();
                        }
                    });
        }
        return true;
    }
    //End of sign out functions
}

И моя модель ChatMessage:

package foo.bar;


import java.util.Date;

public class ChatMessage {

    private String messageText;
    private String messageUser;
    private long messageTime;

    public ChatMessage(String messageText, String messageUser) {
        this.messageText = messageText;
        this.messageUser = messageUser;

        // Initialize to current time
        messageTime = new Date().getTime();
    }

    public ChatMessage(){

    }

    public String getMessageText() {
        return messageText;
    }

    public void setMessageText(String messageText) {
        this.messageText = messageText;
    }

    public String getMessageUser() {
        return messageUser;
    }

    public void setMessageUser(String messageUser) {
        this.messageUser = messageUser;
    }

    public long getMessageTime() {
        return messageTime;
    }

    public void setMessageTime(long messageTime) {
        this.messageTime = messageTime;
    }
}

Манифест:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="foo.bar">

    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

App Gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "ucr.cs100chat"
        minSdkVersion 22
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:26.0.1'
    implementation 'com.android.support.constraint:constraint-layout:1.1.0'
    implementation 'com.google.firebase:firebase-auth:11.0.4'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
    compile 'com.google.firebase:firebase-core:11.0.4'
    compile 'com.firebaseui:firebase-ui-auth:2.3.0'
    compile 'com.google.firebase:firebase-database:11.0.4'
    compile 'com.google.firebase:firebase-auth:11.0.4'
    compile 'com.firebaseui:firebase-ui:0.6.0'
}

apply plugin: 'com.google.gms.google-services'

Проект Gradle:

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {

    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
        classpath 'com.google.gms:google-services:3.2.0' //Firebase requirement

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter() 
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}
0
Aaron 1 Май 2018 в 22:06

1 ответ

Лучший ответ

Этот:

FirebaseDatabase.getInstance().getReference()

Будет извлекать все содержимое базы данных, и под rootNode у вас есть String, поэтому ошибка.

Чтобы решить эту проблему, добавьте child("Message")

FirebaseDatabase.getInstance()
                    .getReference()
                    .child("Message")
                    .push()
                    .setValue(new ChatMessage(input.getText().toString(),
                            FirebaseAuth.getInstance()
                                    .getCurrentUser()
                                    .getDisplayName())
                    );

Также получите дочерний узел сообщения:

FirebaseDatabase.getInstance().getReference().child("Message")
1
Peter Haddad 1 Май 2018 в 20:10