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It will do something different with "static", although the end result will be the same. This is not the same as the difference between using for example public versus private, where it will not do anything different at all (as long as it compiles in both cases). If a line looks like: ... Then it runs once, when the class is initialised. If instead it looks like: ... Then it runs every time you construct an instance of the class, and further each instance of the class will have its own copy of the DAYS variable. This is not just a matter of style; it is a difference in what is happening during execution, and will have an effect (however small) on execution speed and memory use.