in app/build.gradle file buildTypes.each { it.buildConfigField 'String', 'OPEN_WEATHER_MAP_API_KEY', MyOpenWeatherMapApiKey needs to be corrected. The MyOpenWeatherMapApiKey should be specified within '"key"' i.e, '"actual_key"' This may not not be an issue, but needs comment or correction in the source code else the buildconfig.Java will throw an error