you’re right, there are libraries that have been developed for your problems.
Google Gson (https://github.com/google/gson) for JSON serialisation/deserialization
OkHttp (https://github.com/square/okhttp) for async network request
Retrofit (https://github.com/square/retrofit) where we don’t have to build and parse HTTP manually
Glide (https://github.com/bumptech/glide) for async image loading