octal and hexa representation

[Argm Mastoi]

Hi guys,
Why do we need to use octal numbers' and hexa numbers' representation in java?
not clear with their usage and assignment too.

[sabbir kazi]

You may use the following syntax:
String DectoOct = Integer.toOctalString(Integer.parseInt(decimal));
String DectoHex = Integer.toHexString(Integer.parseInt(decimal));