Is it bad practice to use System Properties to store global variables in Java? [closed]

Question

Are they any potential issues (security, performance) or general bad vibes attached to using System.getProperty()/System.setProperty() to store application-wide variables in Java?

Answer 1

Yes it is bad practice, for lots of reasons:

• Performance: the system properties object is a hash table under the hood. Getting and setting is probably 2 orders of magnitude slower than normal getter or setter methods.

• Type safety: unless your variables are all Strings, you have the problem that the values of properties might have the wrong type, resulting in runtime errors, complexity, etc.

• Type conversion cost: for instance, an integer valued property has to be converted on each set and get operation. Not cheap.

• Traceability: it is easier to find references to a real variable than to a named system property.

• Security restrictions: access to the system properties is controlled by the security manager.

And of course, it is unnecessary. If you really need "global" variables, static variables do the job just fine. And if you really need to use a Properties object for holding your application's (non-system) properties, use a separate instance of the Properties object.