[방법-각각의 lib 가 버전이 다를때] ex_) build.gradle(:app) dependence{ ... implementation 'com.squareup.retrofit2:retrofit:2.5.0' implementation 'com.squareup.retrofit2:converter-gson:2.4.0' ... } [방법-lib 버전이 모두 동일할때] dependence{ ... def retrofit_version = "2.5.0" implementation "com.squareup.retrofit2:retrofit:${retrofit_version}" implementation "com.squareup.retrofit2:converter-gson:${retrofit_version}" ...