Using the 'for' statement instead of create new Stream instance.

[kitwtnb]

Issue

• https://github.com/DroidKaigi/conference-app-2017/issues/365

Overview (Required)

• Create new Stream instance every time 'onDraw' is called.
• So using 'for' statement.

Links

• none

[konifar]

Thanks!! LGTM 💯

[eneim]

@konifar @kitwtnb As reference for this blog post, I suspect that this fix gives same result: a new instance of Iterator is implicitly allocated for each iterator for loop call. My suggestion is to use the for loop using index (which simply get the instance from the list reference, no new thing is allocated). Your code looks like 1990 java but ...

P/S: sorry for being a bit OCD >.<. But 60fps FTW :p.

[konifar]

Sorry, Let me confirm your opinion 🤔 You mean following code is better?

for (int i = 0, size = particles.size(); i < size; i++) {
    particles.get(i).draw(canvas, paint);
}

List<Line> lines = createLines(particles);
for (int i = 0, size = lines.size(); i < size; i++) {
    lines.get(i).draw(canvas, paint);
}

[eneim]

@konifar Yes. The point is to prevent object allocation in onDraw, and Iterator by for (Object item: items) will implicitly create one (this is compiler work, we can do nothing).

The second part is to produce new lines for the particle lis, but I think is fine now, so just reduce the allocation as much as possible :D.