Firebase 数据库未从 Firebase 数据库参考中获取数据

Question

一切正常，但 DatabaseReference 没有获取数据，这就像忽略我的代码运行并且我的互联网无法正常工作请帮助我是新来的在这个社区下面是我的代码和图像。

以前它可以工作，但是因为我只是更改了一些代码以使 currentVersion >= vCode 以便即使数据库中的值是

firebase database image

MainActivity.java

public class MainActivity extends AppCompatActivity {
    TextView appName;
    FirebaseUser firebaseUser;
    String currentVersionName;
    long currentVersionCode;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        appName = findViewById(R.id.appName);
        currentVersionName = BuildConfig.VERSION_NAME;
        currentVersionCode = BuildConfig.VERSION_CODE;
        animateAppName();
        netConn();
        FirebaseAuth.getInstance();

    }

    public void applyScreenChange(){
        String sharedPerfId = "MyAppPref";
        SharedPreferences sharedPreferences = getSharedPreferences(sharedPerfId,0);
        boolean isAdvertiserLoggedIn = sharedPreferences.getBoolean("isAdvertiserLoggedIn",false);
        boolean isCreatorLoggedIn = sharedPreferences.getBoolean("isCreatorLoggedIn",false);
        if (isAdvertiserLoggedIn){
            skipSetupToAdvertiser();
        }
        else if (isCreatorLoggedIn){
            skipSetupToCreator();
        }
        else {
            newActivity();
        }
    }

    public void animateAppName(){
        appName.setTranslationY(-1000f);
        appName.animate().translationYBy(1000f).setDuration(500);
    }

    public void netConn(){
        ConnectivityManager connectivityManager = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
        assert connectivityManager != null;
        NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
        if(networkInfo == null || !networkInfo.isConnected() || !networkInfo.isAvailable()){
            AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this).create();
            alertDialog.setTitle("No Internet Connection");
            alertDialog.setMessage("Connect to Network and Then try again");
            alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "Exit", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    MainActivity.super.onBackPressed();
                }
            });
            alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "Retry", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    netConn();
                }
            });
            alertDialog.setCanceledOnTouchOutside(false);
            alertDialog.show();

        }else {

//            Check older version

//            applyScreenChange();


            DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("Version");
            databaseReference.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull DataSnapshot snapshot) {
                    String vName = (String) snapshot.child("latestVersionName").getValue();
                    long vCode = (long) snapshot.child("latestVersionCode").getValue();
                    if (currentVersionName.equals(vName) && currentVersionCode >= vCode){
                        applyScreenChange();

                        // TODO: 16-08-2020 add condition to open app if version is higher
                    }else {
                        Toast.makeText(MainActivity.this, "Old Version", Toast.LENGTH_SHORT).show();
                        AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this).create();
                        alertDialog.setTitle("You're on Older Version");
                        alertDialog.setMessage("This Version is no more supported, Kindly update your App to Continue");
                        alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "Exit", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
                                MainActivity.super.onBackPressed();
                            }
                        });
                        alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "Update", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
//                                startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(getString(R.string.app_link))));
                                Toast.makeText(MainActivity.this, "Kindly Search Sponso on PlayStore and Update", Toast.LENGTH_SHORT).show();
                                finish();
                            }
                        });
                        alertDialog.setCanceledOnTouchOutside(false);
                        alertDialog.show();
                    }
                }

                @Override
                public void onCancelled(@NonNull DatabaseError error) {

                }
            });
        }
    }

    public void newActivity(){
                Intent intent = new Intent(MainActivity.this, AdvertiserCreatorChooser.class);
                startActivity(intent);
                finish();
    }


    public void skipSetupToAdvertiser(){
        firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
        if (firebaseUser!=null) {
                    Intent intent = new Intent(MainActivity.this, AdvertiserHome.class);
                    startActivity(intent);
                    finish();
        }else{
                    Intent intent = new Intent(MainActivity.this, AdvertiserLoginRegister.class);
                    startActivity(intent);
                    finish();
        }
    }

    public void skipSetupToCreator(){
        firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
        if (firebaseUser!=null) {
                    Intent intent = new Intent(MainActivity.this, CreatorHome.class);
                    startActivity(intent);
                    finish();
        }else {
                    Intent intent = new Intent(MainActivity.this, CreatorLoginRegister.class);
                    startActivity(intent);
                    finish();
        }
    }
}

ma​​nifest.xml

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

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

    <application
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:allowBackup="true"
        android:theme="@style/AppTheme">
        <activity android:name=".Advertiser.AdvertiserCampaignUpdate"/>
        <activity android:name=".Advertiser.ui.main.AdvertiserSettings" />
        <activity android:name=".Creator.CreatorRecentlyChat" />
        <activity android:name=".Advertiser.AdvertiserRecentlyChat" />
        <activity android:name=".Advertiser.AdvertiserChatActivity" />
        <activity android:name=".Creator.CreatorChatActivity" />

        <meta-data
            android:name="com.google.android.gms.ads.APPLICATION_ID"
            android:value="@string/app_id" />

        <activity android:name=".Creator.CreatorUserDetails" />
        <activity android:name=".Creator.CreatorList" />
        <activity android:name=".Common.AboutUs" />
        <activity
            android:name=".AdvertiserHome"
            android:label="@string/title_activity_advertiser_home"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".Advertiser.AdvertiserLoginRegister"
            android:label="@string/title_activity_advertiser_login_register"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity android:name=".Common.PrivacyPolicy" />
        <activity android:name=".Common.ChangePassword" />
        <activity android:name=".Creator.CreatorSettings" />
        <activity android:name=".Common.ChangeEmail" />
        <activity android:name=".Advertiser.AdvertiserUserDetails" />
        <activity android:name=".Advertiser.AdvertiserList" />
        <activity
            android:name=".CreatorHome"
            android:label="@string/title_activity_creator_home"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".Creator.CreatorLoginRegister"
            android:label="@string/title_activity_creator_login_register"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity android:name=".AdvertiserCreatorChooser" />
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <meta-data
            android:name="preloaded_fonts"
            android:resource="@array/preloaded_fonts" />
    </application>

</manifest>

依赖

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.1'
    implementation 'com.google.android.material:material:1.2.0'
    implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
    implementation 'com.google.firebase:firebase-database:19.4.0'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'androidx.navigation:navigation-fragment:2.3.0'
    implementation 'androidx.navigation:navigation-ui:2.3.0'
    testImplementation 'junit:junit:4.13'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
    implementation 'com.google.firebase:firebase-auth:19.3.2'
    implementation 'com.google.firebase:firebase-database:19.4.0'
    implementation 'com.firebaseui:firebase-ui-database:6.2.0'
    implementation 'com.google.android.gms:play-services-ads:19.3.0'
    implementation 'com.android.support:multidex:2.0.0'
    implementation 'com.google.firebase:firebase-analytics:17.5.0'
    implementation 'com.google.firebase:firebase-messaging:20.2.4'
    implementation 'com.facebook.android:audience-network-sdk:5.10.1'
}

Answer 1

真正的问题在于 Firebase 数据库

使用 firebase 数据库检查下图

Answer 2

更改
DatabaseReference databaseReference =FirebaseDatabase.getInstance().getReference("Version");
致
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference().child("Version");