if(null!=variable) why not if(variable!=null)

Question

Hi In our company they follow a strict rule of comparing with null values. When I code if(variable!=null) in code review I get comments on this to change it to if(null!=variable). Is there any performance hit for the above code? If anybody explains highly appreciated.

Thanks in advance

Answer 1

I don't see any advantage in following this convention. In C, where boolean types don't exist, it's useful to write

if (5 == variable)

rather than

if (variable == 5)

because if you forget one of the eaqual sign, you end up with

if (variable = 5)

which assigns 5 to variable and always evaluate to true. But in Java, a boolean is a boolean. And with !=, there is no reason at all.

One good advice, though, is to write

if (CONSTANT.equals(myString))

rather than

if (myString.equals(CONSTANT))

because it helps avoiding NullPointerExceptions.

My advice would be to ask for a justification of the rule. If there's none, why follow it? It doesn't help readability.