Question

Just a quick question what would be more expensive in Java?

   double test = 5;
   double test1 = 5;

or

   double test = 5;
   double test1 = test;

Answer 1

Neither. Java has a very good optimiser that will cause the exact same code to be generated in this example.

The compiler looks at the assignment double test1 = test; and can work out that at this point test is a constant equal to 5 and completely optimise the assignment away.

This is also why you shouldn’t be afraid to expand out numeric values, ie.

int timeout = 60 * 60 * 2   // 2 hours in seconds

That entirely aside, this is very much a case of micro-optimisation that will never return anything worth noting. Worry about that network connection that’s holding up the works for several seconds instead.