How am I able to push .txt files to the emulator using Android Studio?
refer johnml1135 answer, but not fully work.
after self investigate, work now:
as official say:
添加文件
将任意文件拖动到模拟器屏幕上。文件将保存到 /sdcard/Download 目录中。使用适合 API 级别的方法导航到文件。例如,对于 API 22,导航路径为:Settings > Device:Storage & USB > Internal Storage > Explore(虚拟 SD 卡)。
and use Drag and Drop actually worked, but use android self installed app Download, then you can NOT find the copied file, for not exist so called /sdcard/Download folder.
finally using other file manager app, like
ES File Explorer

then can see the really path is
/storage/emulated/0/Download/
which contains the copied files, like
/storage/emulated/0/Download/chenhongyu_lixiangsanxun.mp3

after drag and drop more mp3 files:
