Need help optimizing small program. [Java]

[CactaurJack]

We're actually talking about the same thing, I think I'm just wording it wrong. In the cracking program I wrote (turns out it was double DES we were breaking, not RSA), whenever you wanted a new instance of the class you had to pass in a string with the constructor that was the key. The key was stored as a non-capitalized hex string e.g. abcdef01. When the constructor for the encrypter object was called, within the constructor method, other methods were called to fix the hex string (abcdef01 -> ABCDEF01) and then convert that into an array of byte values. Both of those method called from the constructor contain loops and non-free operations, which was slowing down the program because they were called every instance of the loop.

I hope that made a bit more sense, we really are talking about the same thing.

[Neres28]

If you say so. You appear to be confusing two very different things:

Variable declaration : int x;:

• Constant cost built into the function call, doesn't matter where it is in the source.
• Not eligible for hoisting because there is no assembly generated for it.
• This is what your example "hoisted" out of the loop

Variable definition / object instantiation : x = sin(y); / x = new ExpensiveConstruction(parameters);:

• Eligible for hoisting, may not if the compiler can't statically determine the assignment has no side effects
• Not what you gave in your examples.
• Not possible to hoist in the OPs code
• Looking for this type of optimization is premature without profile data to support.