How To Change/Restore User Password in 11G with script

SQL> select password,spare4 from user$ where name='AMIT';

PASSWORD                       SPARE4
------------------------------ ----------------------------------------------------------------------
9DEC0D889E8E9A6B               S:F5DEBF680433864AA5A744C2368D8677A120939D083D74A2F6E99C5952AE

SQL>alter user amit identified by values 'S:F5DEBF680433864AA5A744C2368D8677A120939D083D74A2F6E99C5952AE;9DEC0D889E8E9A6B';

User altered.

Script:
select 'alter user '||name||' identified by values '''||password||''';' from user$ where spare4 is null and password is not null
union
select 'alter user '||name||' identified by values '''||spare4||';'||password||''';' from user$ where spare4 is not null and password is not null;