Converting Signed Int to Unsigned String value in Java

Question

To keep this short, I am getting a signed number, -25771 (in Java), that I need the unsigned String representation of, which is "4294941525". Java thinks the number is signed two's complement, but I need its unsigned value.

I noticed the Javadoc for the toString() method for Integers only converts to signed representation.

Is there not a bitwise operation such as "& 0xFF" that I can do to get the unsigned number?

Hans Brende · Accepted Answer · 2016-07-10 18:43:03Z

9

In Java 8, you can just use Integer.toUnsignedString(int i).

edited Jul 10, 2016 at 18:43

answered May 15, 2015 at 20:46

Hans Brende

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Peter Lawrey · Accepted Answer · 2012-05-16 20:10:27Z

8

I would try

int val = -25771;
System.out.println(Long.toString(val & 0xFFFFFFFFL));

prints

4294941525

or

"" + (val & 0xFFFFFFFFL)

edited May 16, 2012 at 20:10

answered May 16, 2012 at 19:41

Peter Lawrey

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3 Comments

Alex W Over a year ago

Those are both giving me 0 as the output, but the solution posted earlier by aix got a value that was close (the first half of the number was correct).

Peter Lawrey Over a year ago

Can you give an example? You should only get 0, for 0.

Alex W Over a year ago

I figured out the problem: I was using a currentDirectory.getInt(0x011A) method to read a TIFF metadata tag and your solution works now as long as I save the int into an actual int variable. Thanks!

MikeFHay · Accepted Answer · 2014-01-15 14:21:47Z

1

You can use Guava's UnsignedInts.toString, and parseUnsignedInt to reverse the process.

answered Jan 15, 2014 at 14:21

MikeFHay

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