Flutter: Java uses or overrides a deprecated API - firebase

Question

I've been trying to use the auth, firestore firebase in an Android / IOS flutter application, and have been experiencing many different issues, after testing several different versions. Now it's showing me several messages in the build log.
build log
Note:
D:\Flutter\SDK\flutter.pub-cache\hosted\pub.dartlang.org\firebase_core-0.4.3+1\android\src\main\java\io\flutter\plugins\firebase\core\FirebaseCorePlugin.java
uses or overrides a deprecated API. Note: Recompile with
-Xlint:deprecation for details. Note: D:\Flutter\SDK\flutter.pub-cache\hosted\pub.dartlang.org\cloud_firestore-0.13.0+1\android\src\main\java\io\flutter\plugins\firebase\cloudfirestore\CloudFirestorePlugin.java
uses unchecked or unsafe operations. Note: Recompile with
-Xlint:unchecked for details. D8: Cannot fit requested classes in a single dex file (# methods: 81454 > 65536)
com.android.builder.dexing.DexArchiveMergerException: Error while
merging dex archives: The number of method references in a .dex file
cannot exceed 64K. Learn how to resolve this issue at
https://developer.android.com/tools/building/multidex.html
at com.android.builder.dexing.D8DexArchiveMerger.getExceptionToRethrow(D8DexArchiveMerger.java:131)
at com.android.builder.dexing.D8DexArchiveMerger.mergeDexArchives(D8DexArchiveMerger.java:118)
at com.android.build.gradle.internal.transforms.DexMergerTransformCallable.call(DexMergerTransformCallable.java:102)
at com.android.build.gradle.internal.tasks.DexMergingTaskRunnable.run(DexMergingTask.kt:444)
at com.android.build.gradle.internal.tasks.Workers$ActionFacade.run(Workers.kt:335)
at org.gradle.workers.internal.AdapterWorkAction.execute(AdapterWorkAction.java:50)
at org.gradle.workers.internal.DefaultWorkerServer.execute(DefaultWorkerServer.java:47)
at org.gradle.workers.internal.NoIsolationWorkerFactory$1$1$1.create(NoIsolationWorkerFactory.java:65)
at org.gradle.workers.internal.NoIsolationWorkerFactory$1$1$1.create(NoIsolationWorkerFactory.java:61)
at org.gradle.internal.classloader.ClassLoaderUtils.executeInClassloader(ClassLoaderUtils.java:98)
at org.gradle.workers.internal.NoIsolationWorkerFactory$1$1.execute(NoIsolationWorkerFactory.java:61)
at org.gradle.workers.internal.AbstractWorker$1.call(AbstractWorker.java:44)
at org.gradle.workers.internal.AbstractWorker$1.call(AbstractWorker.java:41)
at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:416)
at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:406)
at org.gradle.internal.operations.DefaultBuildOperationExecutor$1.execute(DefaultBuildOperationExecutor.java:165)
at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:250)
at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:158)
at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:102)
at org.gradle.internal.operations.DelegatingBuildOperationExecutor.call(DelegatingBuildOperationExecutor.java:36)
at org.gradle.workers.internal.AbstractWorker.executeWrappedInBuildOperation(AbstractWorker.java:41)
at org.gradle.workers.internal.NoIsolationWorkerFactory$1.execute(NoIsolationWorkerFactory.java:56)
at org.gradle.workers.internal.DefaultWorkerExecutor$3.call(DefaultWorkerExecutor.java:215)
at org.gradle.workers.internal.DefaultWorkerExecutor$3.call(DefaultWorkerExecutor.java:210)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at org.gradle.internal.work.DefaultConditionalExecutionQueue$ExecutionRunner.runExecution(DefaultConditionalExecutionQueue.java:215)
at org.gradle.internal.work.DefaultConditionalExecutionQueue$ExecutionRunner.runBatch(DefaultConditionalExecutionQueue.java:164)
at org.gradle.internal.work.DefaultConditionalExecutionQueue$ExecutionRunner.run(DefaultConditionalExecutionQueue.java:131)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
at java.lang.Thread.run(Thread.java:748) Caused by: com.android.tools.r8.CompilationFailedException: Compilation failed to
complete
at com.android.tools.r8.utils.t.a(:55)
at com.android.tools.r8.D8.run(:11)
at com.android.builder.dexing.D8DexArchiveMerger.mergeDexArchives(D8DexArchiveMerger.java:116)
... 34 more Caused by: com.android.tools.r8.utils.AbortException: Error: null, Cannot fit
requested classes in a single dex file (# methods: 81454 > 65536)
at com.android.tools.r8.utils.Reporter.a(:21)
at com.android.tools.r8.utils.Reporter.a(:7)
at com.android.tools.r8.dex.VirtualFile.a(:33)
at com.android.tools.r8.dex.VirtualFile$h.a(:5)
at com.android.tools.r8.dex.ApplicationWriter.a(:13)
at com.android.tools.r8.dex.ApplicationWriter.write(:35)
at com.android.tools.r8.D8.d(:44)
at com.android.tools.r8.D8.b(:1)
at com.android.tools.r8.utils.t.a(:23)
... 36 more
FAILURE: Build failed with an exception.
What went wrong: Execution failed for task ':app:mergeDexDebug'.
A failure occurred while executing com.android.build.gradle.internal.tasks.Workers$ActionFacade
com.android.builder.dexing.DexArchiveMergerException: Error while merging dex archives:
The number of method references in a .dex file cannot exceed 64K.
Learn how to resolve this issue at https://developer.android.com/tools/building/multidex.html
Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
Get more help at https://help.gradle.org
BUILD FAILED in 4m 33s
flutter doctor -v
[√] Flutter (Channel stable, v1.12.13+hotfix.5, on Microsoft Windows
[Version 10.0.18362.535], locale en-IN)
• Flutter version 1.12.13+hotfix.5 at D:\Flutter\SDK\flutter
• Framework revision 27321ebbad (3 weeks ago), 2019-12-10 18:15:01 -0800
• Engine revision 2994f7e1e6
• Dart version 2.7.0
[√] Android toolchain - develop for Android devices (Android SDK
version 29.0.2)
• Android SDK at C:\Users\admin\AppData\Local\Android\sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-29, build-tools 29.0.2
• Java binary at: D:\Android SDK\jre\bin\java
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
• All Android licenses accepted.
[√] Android Studio (version 3.5)
• Android Studio at D:\Android SDK
• Flutter plugin version 41.1.2
• Dart plugin version 191.8593
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
pubspec
dependencies:
flutter:
sdk: flutter
firebase_auth: ^0.15.3
cloud_firestore: ^0.13.0+1
build.gradle(android)
dependencies {
classpath 'com.android.tools.build:gradle:3.5.0'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
classpath 'com.google.gms:google-services:4.3.0'
}

Answer 1

You need to use the following plugin:
dependencies:
firebase_auth: ^0.15.3
cloud_firestore: ^0.13.0+1
Don't forget to configure firebase:
https://pub.dev/packages/cloud_firestore#setup
https://pub.dev/packages/firebase_auth#usage
Also in your app/build.gradle, increase the minSdkVersion:
Change this:
minSdkVersion 16
into this:
minSdkVersion 23

Answer 2

In order to use minSdkVersion below 21 you will have to configure your app for multidex like this:
android {
defaultConfig {
...
minSdkVersion 15
targetSdkVersion 28
multiDexEnabled true
}
...
}
dependencies {
implementation "androidx.multidex:multidex:2.0.1"
}
After this please run the
flutter pub upgrade
flutter pub get
flutter clean
flutter run
It will still throw the warning after flutter clean, but at least it will be possible for supporting earlier versions.
More to check out on official docs