[oracle] ORA-12505, TNS:listener does not currently know of SID given in connect descriptor

I found some reasons for this exception.they are

1)The name of the database XE by default.so the url will be"jdbc:oracle:thin:@localhost:1521:XE".

2)Make sure that OracleServiceXE,OracleXETNSListener is running.it will be in Control Panel\All Control Panel Items\Administrative Tools\Services