Setting up API Keys

AndroidManiifest.xml

        
    <application>
        ...
        <meta-data
            android:name="com.facebook.sdk.ApplicationId"
            android:value="${facebook_app_id}" />
        <activity
            android:name="com.facebook.FacebookActivity"
            android:configChanges="keyboard|keyboardHidden|screenLayout|screenSize|orientation"
            android:label="@string/app_name" />
        <activity
            android:name="com.facebook.CustomTabActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />

                <data android:scheme="${fb_login_protocol_scheme}" />
            </intent-filter>
        </activity>
    </application>

app_build.gradle

    defaultConfig {
        applicationId "com.andre_max.app_name"
        minSdkVersion 17
        targetSdkVersion 30
        versionCode 1
        versionName "0.1.0"

        vectorDrawables.useSupportLibrary = true

        multiDexEnabled true
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

        // Set the properties within `gradle.properties` into a `Properties` class so that values
        // within `gradle.properties` (e.g. Facebook API key) are accessible in this file.
        Properties properties = new Properties()
        if (rootProject.file("gradle.properties").exists()) {
            properties.load(rootProject.file("gradle.properties").newDataInputStream())
        }

        // Set Twitter keys to Build Config
        buildConfigField('String', 'TWITTER_CONSUMER_KEY', properties.getProperty(twitter_consumer_key, ""))
        buildConfigField('String', 'TWITTER_CONSUMER_SECRET', properties.getProperty(twitter_consumer_secret, ""))

        // Inject the Facebook API key and login protocol scheme into the manifest
        manifestPlaceholders = [
                facebook_app_id         : properties.getProperty("facebook_app_id", ""),
                fb_login_protocol_scheme: properties.getProperty("fb_login_protocol_scheme", "")
        ]
    }

gradle.properties

#<!-- Facebook consumer key and secret -->
facebook_app_id"=""
fb_login_protocol_scheme=""

#<!-- Twitter consumer key and secret -->
twitter_consumer_key=""
twitter_consumer_secret=""