Execution failed for task ':app:compileDebugJavaWithJavac'. React Native application for Android

I am trying to launch android emulator from my React Native application, But, Its throwing following error and emulator not able to launch in my MAC system.

Error is

    Configure project :app
     WARNING: Configuration 'compile' is obsolete and has been replaced with 'implementation' and 'api'.
     It will be removed at the end of 2018. For more information see: http://d.android.com/r/tools/update-dependency-configurations.html

     Configure project :react-native-app
     WARNING: Configuration 'compile' is obsolete and has been replaced with 'implementation' and 'api'.
     It will be removed at the end of 2018. For more information see: http://d.android.com/r/tools/update-dependency-configurations.html
     WARNING: Configuration 'testCompile' is obsolete and has been replaced with 'testImplementation' and 'testApi'.
     It will be removed at the end of 2018. For more information see: http://d.android.com/r/tools/update-dependency-configurations.html
    WARNING: Configuration 'testApi' is obsolete and has been replaced with 'testImplementation'.
     It will be removed at the end of 2018. For more information see: http://d.android.com/r/tools/update-dependency-configurations.html

      Configure project :react-native-version-number
     WARNING: Configuration 'compile' is obsolete and has been replaced with 'implementation' and 'api'.
     It will be removed at the end of 2018. For more information see: http://d.android.com/r/tools/update-dependency-configurations.html
     WARNING: The specified Android SDK Build Tools version (23.0.1) is ignored, as it is below the minimum supported version (27.0.3) for
 Android Gradle Plugin 3.1.4.
     Android SDK Build Tools 27.0.3 will be used.
     To suppress this warning, remove "buildToolsVersion '23.0.1'" from your build.gradle file, as each version of the Android Gradle Plugin
 now has a default version of the build tools.

     Download https://dl.google.com/dl/android/maven2/com/android/support/multidex/1.0.2/multidex-1.0.2.pom
     Download https://dl.google.com/dl/android/maven2/com/android/support/multidex/1.0.2/multidex-1.0.2.aar

      Task :app:compileDebugJavaWithJavac FAILED
     /Users/anilkumar/Documents/projectName/android/app/src/main/java/com/projectName/MainApplication.java:19:
 error: cannot find symbol
           return BuildConfig.DEBUG;
                  ^
       symbol: variable BuildConfig
     1 error



My build.gradle file

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

    buildscript {
        ext {
            buildToolsVersion = "27.0.3"
            minSdkVersion = 16
            compileSdkVersion = 27
            targetSdkVersion = 26
            supportLibVersion = "27.1.1"
        }
        repositories {
            google()
            jcenter()
        }
        dependencies {
            classpath 'com.android.tools.build:gradle:3.1.4'

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

    allprojects {
        repositories {
            mavenLocal()
            google()
            jcenter()
            maven {
                // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
                url "$rootDir/../node_modules/react-native/android"
            }
        }
    }


    task wrapper(type: Wrapper) {
        gradleVersion = '4.4'
        distributionUrl = distributionUrl.replace("bin", "all")
    }

I am very new to React Native, Can anyone suggest me how to fix this?