error with Ionic App: Execution failed for task ':transformDexWithDexForRelease'

Question

The Task.leftShift(Closure) method has been deprecated and is scheduled to be removed in Gradle 5.0. Please use Task.doLast(Action) instead.
    at build_14nw1tmmrdvevki8jo499flje.run(/home/chaitanya/Videos/feb27/client/ionic/platforms/android/build.gradle:142)
publishNonDefault is deprecated and has no effect anymore. All variants are now published.
:preBuild UP-TO-DATE
:CordovaLib:preBuild UP-TO-DATE
:CordovaLib:preReleaseBuild UP-TO-DATE
:CordovaLib:checkReleaseManifest
:CordovaLib:processReleaseManifest
:preReleaseBuild
:CordovaLib:compileReleaseAidl
:compileReleaseAidl
:CordovaLib:packageReleaseRenderscript NO-SOURCE
:compileReleaseRenderscript
:checkReleaseManifest
:generateReleaseBuildConfig
:prepareLintJar UP-TO-DATE
:generateReleaseResValues
:generateReleaseResources
:CordovaLib:compileReleaseRenderscript
:CordovaLib:generateReleaseResValues
:CordovaLib:generateReleaseResources
:CordovaLib:packageReleaseResources
:mergeReleaseResources
:createReleaseCompatibleScreenManifests
:processReleaseManifest
:splitsDiscoveryTaskRelease
:CordovaLib:platformAttrExtractor
:CordovaLib:generateReleaseBuildConfig
:CordovaLib:prepareLintJar UP-TO-DATE
:CordovaLib:javaPreCompileRelease
:CordovaLib:processReleaseJavaRes NO-SOURCE
:compileReleaseNdk NO-SOURCE
:mergeReleaseShaders
:compileReleaseShaders
:generateReleaseAssets
:CordovaLib:mergeReleaseShaders
:CordovaLib:compileReleaseShaders
:CordovaLib:generateReleaseAssets
:CordovaLib:mergeReleaseAssets
:mergeReleaseAssets
:mergeReleaseJniLibFolders
:CordovaLib:compileReleaseNdk NO-SOURCE
:CordovaLib:mergeReleaseJniLibFolders
:CordovaLib:transformNativeLibsWithMergeJniLibsForRelease
:CordovaLib:transformNativeLibsWithIntermediateJniLibsForRelease
:processReleaseJavaRes NO-SOURCE
:CordovaLib:processReleaseResources
:processReleaseResources
:generateReleaseSources
:CordovaLib:generateReleaseSources
:CordovaLib:compileReleaseJavaWithJavacNote: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.

:CordovaLib:transformClassesAndResourcesWithPrepareIntermediateJarsForRelease
:javaPreCompileRelease
:compileReleaseJavaWithJavacNote: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: /home/chaitanya/Videos/feb27/client/ionic/platforms/android/src/org/apache/cordova/file/AssetFilesystem.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint: unchecked for details.

:compileReleaseSources
:transformClassesWithPreDexForRelease
:transformDexWithDexForRelease FAILED

:

FAILURE: Build failed with an exception.

• What went wrong: Execution failed for task ':transformDexWithDexForRelease'.

  com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: com.android.dex.DexException: Multiple dex files define Lokhttp3/Address;

• Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

• Get more help at https://help.gradle.org

BUILD FAILED in 4s
39 actionable tasks: 37 executed, 2 up-to-date
Error: /home/chaitanya/Videos/feb27/client/ionic/platforms/android/gradlew:

Command failed with exit code 1 Error output: Note: Some input files use or override a deprecated API. Note: Recompile with -Xlint:deprecation for details. Note: Some input files use or override a deprecated API. Note: Recompile with -Xlint:deprecation for details. Note: /home/chaitanya/Videos/feb27/client/ionic/platforms/android/src/org/apache/cordova/file/AssetFilesystem.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details.

FAILURE: Build failed with an exception.

• What went wrong: Execution failed for task ':transformDexWithDexForRelease'.

  com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: com.android.dex.DexException: Multiple dex files define Lokhttp3/Address;

• Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

• Get more help at https://help.gradle.org

BUILD FAILED in 4s

Answer 1

Since Gradle 3.2 the << (leftShift) operator is deprecated. The operator can confusepeople, because without the operator we would configure the deprecatedSample task, instead of adding the action statement: println 'Sample task'.

task deprecatedSample << {
    println 'Sample task'
}

To have no confusion we should use the doLast method of a task to add the action statement println 'Sample task'.

task newSample {
    doLast {
        println 'Sample task'
    }
}