Using NOT operator in IF conditions

Question

Is it really a good practice to avoid using NOT operator in IF conditions in order to make your code better readable  I heard the if  doSomething    is better then if   doSomething

User · Accepted Answer

It really depends on what you re trying to accomplish   If you have no else clause then if  doSomething    seems fine   However  if you have  if  doSomething                else          do something else     I d probably reverse that logic to remove the   operator and make the if clause slightly more clear

User · Answer

In general    is a perfectly good and readable boolean logic operator  No reason not to use it unless you re simplifying by removing double negatives or applying Morgan s law      A    A   or     A    B    A  amp  B   As a rule of thumb  keep the signature of your boolean return methods mnemonic and in line with convention  The problem with the scenario that  hvgotcodes proposes is that of course a b and c d e are not very friendly examples to begin with  Suppose you have a Flight and a Seat class for a flight booking application  Then the condition for booking a flight could perfectly be something like  if flight isActive    amp  amp   seat isTaken            book the seat     This perfectly readable and understandable code  You could re-define your boolean logic for the Seat class and rephrase the condition to this  though   if flight isActive    amp  amp  seat isVacant            book the seat     Thus removing the   operator if it really bothers you  but you ll see that it all depends on what your boolean methods mean

User · Answer

I never heard of this one before   How is   if  doSomething        else         blah     better than  if   doSomething            blah     The later is more clear and concise   Besides the   operator can appear in complex conditions such as   a    b   How do you avoid it then   Use the   operator when you need

User · Answer

It is generally not a bad idea to avoid the  -operator if you have the choice  One simple reason is that it can be a source of errors  because it is possible to overlook it  More readable can be  if conditionA  false  in some cases  This mainly plays a role if you skip the else part   If you have an else-block anyway you should not use the negation in the if-condition    Except for composed-conditions like this   if  isA    amp  amp  isB    amp  amp   isNotC      Here you have to use some sort of negation to get the desired logic  In this case  what really is worth thinking about is the naming of the functions or variables  Try to name them so you can often use them in simple conditions without negation   In this case you should think about the logic of isNotC   and if it could be replaced by a method isC   if it makes sense   Finally your example has another problem when it comes to readability which is even more serious than the question whether to use negation or not  Does the reader of the code really knows when doSomething   returns true and when false  If it was false was it done anyway  This is a very common problem  which ends in the reader trying to find out what the return values of functions really mean

User · Answer

try like this  if    a   b           blahblah     It s same with  if  a   b     else          blahblah

User · Answer

As a general statement  its good to make your if conditionals as readable as possible   For your example  using   is ok   the problem is when things look like  if   a b  amp  amp  c d e      f    you might want to do something like  bool isOk   a b  bool isStillOk   c d e bool alternateOk    f   then your if statement is simplified to  if    isOk  amp  amp  isStillOk     alternateOk    It just makes the code more readable   And if you have to debug  you can debug the isOk set of vars instead of having to dig through the variables in scope   It is also helpful for dealing with NPEs -- breaking code out into simpler chunks is always good

User · Answer

No  there is absolutely nothing wrong with using the   operator in if  then  else statements   The naming of variables  and in your example  methods is what is important  If you are using   if  isPerson               Nothing wrong with this   However   if  balloons               method is named badly   It all comes down to readability  Always aim for what is the most readable and you won t go wrong  Always try to keep your code continuous as well  for instance  look at Bill the Lizards answer

[java] Using NOT operator in IF conditions

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