This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
Bitwise operators are normally not used for business logic, much more for low level (on bytes etc) operations. One place where they are used much is cryptography and (again, low level) communication protocols.
As for the toHexStrring method:
Seems a bit more readable to me. Note the & bitwise operator that converts the (possibly negative) signed byte value to a possitive int.
[EDIT] this is a bit unfair of course, since String.format() almost certainly will use shift operators to generate the 2 digit hexadecimal string similar to the code given in the post above
When I need bitwise operators, I'm usually working with an embedded device or storage format, that uses very tight packing of data.
Imagine if you have several integer variables who's value will never exceed a certain limit, then you can pack them together tightly to save space.
An example of such an application I'm currently working with: In a particular resource index file format, there's a 4 byte field that encodes the index of the archive where a resource is located, as well as the index of the resource within that archive. The 12 most significant bits stand for the archive index, the next 6 bits stand for a special value. The 14 least significant bits stand for the resource index.
I can then retrieve all the values as follows:
The shift (>>) is used to 'cut off' the bits to the right of the required index. Note that "resource" doesn't need to be shifted, because it is located at the least-significant-bit of the value.
The mask (&) is used to 'zero out' the bits to the left of the required index. Note that "archive" requires a mask, even though it's located at the most-significant-bit, because the shift operator will fill the most significant bits with 1, instead of 0, if value happens to be negative. Here's what really happens:
You can use the & operator to dispense with division in this exampleIt gives a slight performance advantage over % 2, but there is a subtle difference in its behaviour. You might find out what the subtle difference is if you change that code by replacing & 1 by % 2.
You can use the & and | operators to create and use masks.
You can use the shift operators instead of multiplying or dividing by 2, 4, 8, etc. Try this old thread and see whether I have actually given you the correct link