unable to take database online in ORACLE 11g

Error : ORA-01113: file 4 needs media recovery

I got the below error during database recovery (after performing the database backup using HOT backup method .)
 alter database datafile '/disk1/dev/data/users01.dbf' online;

ORA-01113: file 4 needs media recovery
ORA-01110: data file 4: '/disk1/dev/data/users01.dbf'

Resolution 

In order to make the database online you have to follow the below steps

1. alter database datafile  '/disk1/dev/data/users01.dbf' offline;

2. cp users01.dbf /disk1/dev/data/ # From hot backup location.

3. recover datafile '/disk1/dev/data/user01.dbf';

4.alter database datafile 'disk1/dev/data/users01.dbf' online;