优化Java中的OBJ文件（3D模型）加载

Question

Before I begin I apologize for my lack of comments in my code. I am currently making a OBJ file loader (in java.) Although my code works as expected for small files, when files become large (for example I am currently attempting to load a obj file which has 25,958 lines) my entire system crashes. I recently migrated my entire project over from C++ which could load this model quickly. I utilized a profiler alongside a debugger to determine where the entire process crashes my system. I noticed a few things; first, it was hanging at the initiation process; second, my heap was nearly completely used up (I used up about 90% of the heap.) My code can be found here: http://pastebin.com/VjN0pzyi I was curious about methods I could employ to optimize this code.

Answer 1

When you're really low on memory, everything slows down a lot. I guess you should improve you coding skills, things like

startChar = line[i].toCharArray()[k];

probably don't get optimized to

startChar = line[i].charAt(k);

automagically. Maybe interning your strings could save a lot of memory, try String.intern or Guava Interner .

The Hotspot loves short methods, so refactor. The code as it is hard to read and I guess that given its size no optimizations get done at all!

Answer 2

I know this is an old question, but I wanted to throw in my two cents on your performance issues. You're saying that your code not only runs slow, but it takes up 90% of the heap. I think saying 90% is an egregious exaggeration, but this still allows me to point out the biggest flaw with Java game development. Java does not support value types, such as structs. That means that in order to gain speed you're required to avoid OOP, because every time you instance a class for your loader it is allocated onto the heap. You must then invariably wait for GC to kick in to get rid of the clutter and left over instances that your loader created. Now take a language like C# as an example of how to create a real language . C# fully supports structs. You could replace every class of your loader with them. Faces, groups, Vertex, Normal, classes are then treated as value types; they are deleted when the stack unwinds. No garbage is generated, or at least very little if you're required to use a class or two.

In my opinion, don't use Java for game development. I used it for years before discovering C#. Strictly my opinion, here, but Java is a horrible language; I will never use it again.