What does this boolean “(number & 1) == 0” mean?

Question

On CodeReview I posted a working piece of code and asked for tips to improve it. One I got was to use a boolean method to check if an ArrayList had an even number of indices

Answer 1

The & operator in Java is the bitwise-and operator. Basically, (number & 1) performs a bitwise-and between number and 1. The result is either 0 or 1, depending on whether it's even or odd. Then the result is compared with 0 to determine if it's even.

Here's a page describing bitwise operations.