What does this sign exactly mean? |=

Question

|=

I\'m curious to learn about this operator, I\'ve seen this notation used while setting flags in Java.

for example:

notification.flags |=         


        

Answer 1

It is called bitwise or operator. For example,

5     = 0000 0101
2     = 0000 0010
5 | 2 = 0000 0111
      = 14

So, this concept is used when a same option can use multiple values.

As an example, consider a variable flags equal to one.

int flags = 1;

Now, if a flag value of 4 is added to it with bitwise or,

flags |= 4;  // 0

You can determine whether 4 was applied on flags with the bitwise and.

if (flags & 4 == 4)  // returns true

If that flag has been applied on the flags, bitwise and returns flag. In this way we can use bitwise and & bitwise or.

Hope this helps.