Issue #28596: The preferred encoding is UTF-8 on Android.

Lib/_bootlocale.py

@@ -14,6 +14,12 @@ else:
     try:
         _locale.CODESET
     except AttributeError:
+        if hasattr(sys, 'getandroidapilevel'):
+            # On Android langinfo.h and CODESET are missing, and UTF-8 is
+            # always used in mbstowcs() and wcstombs().
+            def getpreferredencoding(do_setlocale=True):
+                return 'UTF-8'
+        else:
             def getpreferredencoding(do_setlocale=True):
                 # This path for legacy systems needs the more complex
                 # getdefaultlocale() function, import the full locale module.

Lib/locale.py

@@ -618,6 +618,12 @@ else:
     try:
         CODESET
     except NameError:
+        if hasattr(sys, 'getandroidapilevel'):
+            # On Android langinfo.h and CODESET are missing, and UTF-8 is
+            # always used in mbstowcs() and wcstombs().
+            def getpreferredencoding(do_setlocale = True):
+                return 'UTF-8'
+        else:
             # Fall back to parsing environment variables :-(
             def getpreferredencoding(do_setlocale = True):
                 """Return the charset that the user is likely using,

Misc/NEWS

@@ -13,6 +13,9 @@ Core and Builtins
 - Issue #18896: Python function can now have more than 255 parameters.
   collections.namedtuple() now supports tuples with more than 255 elements.
 
+- Issue #28596: The preferred encoding is UTF-8 on Android. Patch written by
+  Chi Hsuan Yen.
+
 - Issue #26919: On Android, operating system data is now always encoded/decoded
   to/from UTF-8, instead of the locale encoding to avoid inconsistencies with
   os.fsencode() and os.fsdecode() which are already using UTF-8.