Yes, as @GeorgeChen 's comment said. By now as I known, there is not any SDK for Azure Data Lake Storage Gen2, so the only solution is to use its REST APIs.
There is a very similar SO thread Upload data to the Azure ADLS Gen2 from on-premise using Python or Java which you can refer to, my answer for it to post the Python script which defines 7 functions to help using REST APIs include auth, mkfs, mkdir, touch_file, append_file, flush_file and mkfile.
For using Java, you can refer to my code in Python to write your Java code with okhttp.
Update: I reviewed Azure offical documents and searched the offical GitHub repos for ADLS Gen2, there is a public preview version of ADLS Gen2 SDK named Azure File Data Lake client library for Java. I see it default used the Netty HTTP client, but you can use OkHTTP as the Alternate HTTP client as the content of README said, so I think you can try to use it with the alternate HTTP client OkHTTP for Android.