Assuming you are new to Android AND Java, I think you should learn Java the language, following Oracle tutorials and/or a good book, but stopping when it comes to API's, other than the most basic ones (java.lang and java.util packages). Here I would jump to Android tutorials and learn about Java API's as necessary. While Android uses a lot of Java API's, some are totally useless, like everything related to GUI. For GUI, Android provides its own API's, which are quite different. As you learn Java, don't even get into GUI, stay with console applications.
Perfect answer, IMO.