I used Android Studio 3.0 Beta 2 with the following gradle settings

I can search the RxRoom but no Room class founded. After following the instruction [Add Components](https://developer.android.com/topic/libraries/architecture/adding-components.html) , I cannot use Room class in my Fragment.

This class is in the seperate module, the app module does not contains any room library dependency. 

The error showed "Cannot resolve symbol Room" in IDE. 

[![enter image description here](https://i.stack.imgur.com/shQfF.png)](https://i.stack.imgur.com/shQfF.png)

build.gradle

```
apply plugin: 'com.android.library'

android {
    compileSdkVersion 26
    buildToolsVersion "26.0.1"

    defaultConfig {
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        javaCompileOptions {
            annotationProcessorOptions {
                arguments = ["room.schemaLocation":
                                     "$projectDir/schemas".toString()]
            }
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    compileOptions {
        targetCompatibility 1.8
        sourceCompatibility 1.8
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:26.0.2'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    implementation 'com.android.support:design:26.0.2'
    implementation 'com.android.support:support-v4:26.0.2'
    implementation 'com.android.support:recyclerview-v7:26.0.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation('com.android.support.test.espresso:espresso-core:3.0.1', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    implementation "android.arch.persistence.room:runtime:1.0.0-alpha9"
    annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha9"
    testImplementation "android.arch.persistence.room:testing:1.0.0-alpha9"
    implementation "android.arch.persistence.room:rxjava2:1.0.0-alpha9"
}

```

**Updated** 
I have tried to downgrade the room library to alpha8 first and the Room class come back now. I have no idea why this class disappeared in the alpha9 but at least it is the workaround.