Is it good practice to use the xor operator for boolean checks

Question

I personally like the exclusive or     operator when it makes sense in the context of boolean checks because of its conciseness   I much prefer to write  if  boolean1   boolean2        do it     than  if  boolean1  amp  amp   boolean2      boolean2  amp  amp   boolean1         do it     but I often get confused looks from other experienced Java developers  not just the newbies   and sometimes comments about how it should only be used for bitwise operations    I m curious as to the best practices regarding the usage of the   operator

User · Answer

As a bitwise operator  xor is much faster than any other means to replace it  So for performance critical and scalable calculations  xor is imperative   My subjective personal opinion  It is absolutely forbidden  for any purpose  to use equality     or     for booleans  Using it shows lack of basic programming ethics and fundamentals  Anyone who gives you confused looks over   should be sent back to the basics of boolean algebra  I was tempted to write  to the rivers of belief  here

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I find that I have similar conversations a lot   On the one hand  you have a compact  efficient method of achieving your goal   On the other hand  you have something that the rest of your team might not understand  making it hard to maintain in the future   My general rule is to ask if the technique being used is something that it is reasonable to expect programmers in general to know   In this case  I think that it is reasonable to expect programmers to know how to use boolean operators  so using xor in an if statement is okay   As an example of something that wouldn t be okay  take the trick of using xor to swap two variables without using a temporary variable   That is a trick that I wouldn t expect everybody to be familiar with  so it wouldn t pass code review

User · Answer

I personally prefer the  boolean1   boolean2  expression due to its succinctness   If I was in your situation  working in a team   I would strike a compromise by encapsulating the  boolean1   boolean2  logic in a function with a descriptive name such as  isDifferent boolean1  boolean2     For example  instead of using  boolean1   boolean2   you would call  isDifferent boolean1  boolean2   like so   if  isDifferent boolean1  boolean2         do it     Your  isDifferent boolean1  boolean2   function would look like   private boolean isDifferent boolean1  boolean2        return boolean1   boolean2      Of course  this solution entails the use of an ostensibly extraneous function call  which in itself is subject to Best Practices scrutiny  but it avoids the verbose  and ugly  expression   boolean1  amp  amp   boolean2      boolean2  amp  amp   boolean1

User · Answer

If the usage pattern justifies it  why not  While your team doesn t recognize the operator right away  with time they could  Humans learn new words all the time  Why not in programming    The only caution I might state is that     doesn t have the short circuit semantics of your second boolean check  If you really need the short circuit semantics  then a static util method works too   public static boolean xor boolean a  boolean b        return  a  amp  amp   b      b  amp  amp   a

User · Answer

I think you ve answered your own question - if you get strange looks from people  it s probably safer to go with the more explicit option   If you need to comment it  then you re probably better off replacing it with the more verbose version and not making people ask the question in the first place

User · Answer

You could always just wrap it in a function to give it a verbose name   public static boolean XOR boolean A  boolean B        return A   B      But  it seems to me that it wouldn t be hard for anyone who didn t know what the   operator is for to Google it really quick  It s not going to be hard to remember after the first time  Since you asked for other uses  its common to use the XOR for bit masking    You can also use XOR to swap the values in two variables without using a third temporary variable      Swap the values in A and B A    B  B    A  A    B    Here s a Stackoverflow question related to XOR swapping

User · Answer

if  boolean1  amp  amp   boolean2      boolean2  amp  amp   boolean1           do it       IMHO this code could be simplified   if boolean1    boolean2          do it

User · Answer

I recently used an xor in a JavaScript project at work and ended up adding 7 lines of comments to explain what was going on  The justification for using xor in that context was that one of the terms  term1 in the example below  could take on not two but three values  undefined  true or false while the other  term2  could be true or false  I would have had to add an additional check for the undefined cases but with xor  the following was sufficient since the xor forces the first term to be first evaluated as a Boolean  letting undefined get treated as false   if  term1   term2          It was  in the end  a bit of an overkill  but I wanted to keep it in there anyway  as sort of an easter egg

User · Answer

You can simply use    instead

User · Answer

With code clarity in mind  my opinion is that using XOR in boolean checks is not typical usage for the XOR bitwise operator  From my experience  bitwise XOR in Java is typically used to implement a mask flag toggle behavior   flags   flags   MASK    This article by Vipan Singla explains the usage case more in detail   If you need to use bitwise XOR as in your example  comment why you use it  since it s likely to require even a bitwise literate audience to stop in their tracks to understand why you are using it

User · Answer

I think it d be okay if you commented it  e g          XOR

User · Answer

is OK to compare two variables  It doesn t work  though  with multiple comparisons

User · Answer

str contains         str startsWith  not      looks better for me than  str contains          str startsWith  not

[java] Is it good practice to use the xor operator for boolean checks?

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