java - FirebaseAuth.getInstance() 返回 null
问题描述
我从 Firebase 获取 mAuth.getInstance() 时遇到问题。它总是返回 null。由于这个问题,整个应用程序崩溃,我无法继续。我怎么解决这个问题?
我试图修改 gradle 版本,但没有解决任何问题。我在这里添加了必要的代码片段。
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.smartfarmandroidapp"
xmlns:tools="http://schemas.android.com/tools">
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
tools:node="replace"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.SmartFarmAndroidApp">
<activity
android:name=".MVVM.View.Activities.DrawerActivity"
android:label="Drawer Activity"
android:theme="@style/AppTheme.NoActionBar"
android:windowSoftInputMode="adjustPan"/>
<activity android:name=".MVVM.View.Activities.MainActivity" />
<activity android:name=".MVVM.View.Activities.LoginActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
摇篮:模块
apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'
android {
compileSdkVersion 30
buildToolsVersion "30.0.3"
defaultConfig {
applicationId "com.example.smartfarmandroidapp"
minSdkVersion 16
targetSdkVersion 30
versionCode 1
versionName "1.0"
multiDexEnabled true
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
}
dependencies {
implementation 'androidx.appcompat:appcompat:1.3.0'
implementation 'com.google.android.material:material:1.3.0'
implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
//Firebase Authentication
implementation platform('com.google.firebase:firebase-bom:28.0.1')
implementation 'com.firebaseui:firebase-ui-auth:7.1.1'
implementation 'com.google.firebase:firebase-auth'
}
摇篮:项目
// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
repositories {
google()
jcenter()
mavenCentral()
}
dependencies {
classpath 'com.android.tools.build:gradle:4.1.2'
classpath 'androidx.navigation:navigation-safe-args-gradle-plugin:2.3.5'
classpath 'com.google.gms:google-services:4.3.8'
// 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
}
登录活动.java
private static final int SIGN_IN = 42;
private static final String TAG = "LoginActivity";
private FirebaseAuth mAuth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FirebaseApp.initializeApp(this);
mAuth = FirebaseAuth.getInstance(); //This line returns null
}
@Override
public void onStart() {
super.onStart();
FirebaseUser currentUser = mAuth.getCurrentUser();
}
我得到的整个错误异常如下:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.smartfarmandroidapp, PID: 16328
java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.firebase.auth.FirebaseUser com.google.firebase.auth.FirebaseAuth.getCurrentUser()' on a null object reference
at com.example.smartfarmandroidapp.MVVM.View.Activities.LoginActivity.onStart(LoginActivity.java:191)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1435)
at android.app.Activity.performStart(Activity.java:8024)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3475)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
解决方案
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