Your code should not reference the /sdcard path directly, which is platform-dependent. You should use Environment.getExternalStorageDirectory().getPath() instead.
Similarly, do not reference the /data/data/ path directly, as it can vary in multi-user scenarios. You should use Context.getFilesDir().getPath() instead.
For more information, please see the documentation for android.os.Environment and android.content.Context.
This check is an adaptation of the SdCardPath rule of Android Lint.