Java "&" Operator

Question

Could somebody explain me why System.out.println((12 & 9)); prints 8, please?

I do not understand the logic of the & operator at this context.

Thanks!

& is a bitwise and operator. – Aniket Thakur Apr 08 '14 at 14:20 — Aniket Thakur, Apr 08 '14 at 14:20
https://en.wikipedia.org/wiki/Bitwise_operation#AND – Steve Kuo Apr 08 '14 at 15:06 — Steve Kuo, Apr 08 '14 at 15:06

score 18 · Answer 1 · answered Apr 08 '14 at 14:19

18

It's binary.

12 is 1100 and 9 is 1001.

Applying the logical "and" & operator gives 1000, which is 8.

answered Apr 08 '14 at 14:19

AntonH

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Sireesh Yarlagadda · Accepted Answer · 2014-04-13T00:55:24.440

8

It is Binary representation. (Machine Understandable language)
Here first place resembles  value - 1 (Right to Left)
Second place resembles  value - 2 (Right to Left)
Third place resembles  value - 4 (Right to Left)
Fourth place resembles  value - 8 (Right to Left)

& says 1 and 1 is true(i.e., 1), rest of combinations are false (i.e., 0)

     12 - 1100
      9 - 1001
===============
      8 - 1000

edited Apr 13 '14 at 00:55

answered Apr 08 '14 at 14:25

Sireesh Yarlagadda

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score 4 · Answer 3 · answered Apr 08 '14 at 14:22

4

& is a bitwise and operator.

12 = 1100
9 = 1001
1100 & 1001 = 1000
1000 = 8

answered Apr 08 '14 at 14:22

Aniket Thakur

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score 1 · Answer 4 · answered Apr 08 '14 at 14:31

The logic for printing 8 is the same as System.out.println((12 + 9)); prints 21.

The operators get preference over the called method, so and operation is performed first then anything else is let to happen.

Here you are doing simple logical and which should result in 8, as following:

12 is 1100 and 9 is 1001.

& operation will result in 1000. where 1000 is 8.

Java "&" Operator

4 Answers4