Java operator to check if either conditions are false, but not both or none

Question

Is there an operator in Java that will give a result of false if either conditions are false, but if both are true or both false the result will be true?

I have some code that relies on a user entering some values for a process to run. As the user should only be able to enter x or y but not both or none I would like to show an error message in this case.

Jon Skeet · Accepted Answer · 2010-01-11 16:02:41Z

24

You want XNOR, basically:

if (!(a ^ b))

or (more simply)

if (a == b)

where a and b are the conditions.

Sample code:

public class Test { public static void main(String[] args) { xnor(false, false); xnor(false, true); xnor(true, false); xnor(true, true); } private static void xnor(boolean a, boolean b) { System.out.printf("xnor(%b, %b) = %b\n", a, b, a == b); } }

Produces this truth table;

xnor(false, false) = true xnor(false, true) = false xnor(true, false) = false xnor(true, true) = true

edited Jan 11, 2010 at 16:02

answered Jan 11, 2010 at 15:57

Jon Skeet

1.5m893 gold badges9.3k silver badges9.3k bronze badges

Sign up to request clarification or add additional context in comments.

12 Comments

jdmichal Over a year ago

Jon, it would probably be beneficial to show the full logic table for the XOR operator in this case. I would do it here, but the comment formatting is horrible for this.

James Goodwin Over a year ago

Thanks, that was what I was looking for! I knew there was an operator, just couldn't remember it :)

Jon Skeet Over a year ago

@James: I've edited this with a simpler way of doing this - the equality operator!

jdmichal Over a year ago

Also, yes, != is simpler. But !XOR is the correct boolean operator for this case. So I still like your answer the best.

jdmichal Over a year ago

This question was given in the context of Java. In Java, the ^ symbol represents the bit-operation XOR.

|

Collectives™ on Stack Overflow

Java operator to check if either conditions are false, but not both or none

1 Answer 1

12 Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

12 Comments

Related