Set the rest of the bits to 1 in Java

Question

I need some help with bitwise operations. I have number(64 bit) were first 16 bits are meaningful, and I'd like to set rest of them to "1"

00000000 11000001 00000000 00000000 ... <- currrent value

00000000 11000001 11111111 11111111 ... <- result I am trying to achieve

P.S. Oh, yeah! Sometimes, to solve - you just need to write out your task:)

I got it: value |= (-1 << bitsCount);

bitsCount - count of my meaningful bits

You say your number is 64 bits, then you give 32 bit values. Which is it? — rgettman, Nov 17 '14 at 23:13
Please clarify which bits in your diagram are the 'first' bits. Tell us the base-10 value of 'current value'. — Radiodef, Nov 17 '14 at 23:16

score 5 · Accepted Answer · answered Nov 17 '14 at 23:16

5

Use the bitwise OR operator:

value |= 0xFFFF

1111111111111111₂ = 2¹⁶ - 1= FFFF₁₆

answered Nov 17 '14 at 23:16

August

score 2 · Answer 2 · answered Nov 17 '14 at 23:16

2

OR it with 11111111 11111111. foo | 0xffff

answered Nov 17 '14 at 23:16

Steve Kuo

2 Answers2