Java并发，读取文件创建对象并存储它们

Question

I'm currently using java.nio to read files (using Files.readAllLines ) and then each line is passed to create an object [ new Object(line)] and the object is added to a collection.

Each file is parsed differently so that there is 3 types of objects, 2 of those are added to a map and they should be done first as they third adds to a set and gets added to a variable inside both of the previous maps [using something like that:

get(var).x.add(Object)].

I don't really understand how to code concurrently and was having trouble finding anything close to this but I imagine it's possible to use concurrency to create the first two collections or to use it in all three and have do the final lot last (or get it to wait and do it later if the variables it needs to edit haven't been set yet).

Any help would be appreciated and if you need any clarification in what I'm looking for just ask.

Answer 1

So you have 3 files and 2 of which are to put into a map, and the last file is for adding to some value of the map, right?

You could create threads for each of two files and put data into map. Important thing here is that you must use concurrent data structure like ConcurrentHashMap or synchronized map.

Answer 2

I would use the following global steps to do this concurrently:

1. Create a threadpool of a certain size: Executors. newFixedThreadPool(someSize) Executors. newFixedThreadPool(someSize)
2. Create three concurrent/synchronized sets. One for each object type: Collections.synchronizedSet(new HashSet<YourObjectType>());
3. Use the threadpool to work through all the files adding to the synchronized sets when appropriate
4. When all files have been processed the first to lists/collections have the initial objects, then loop through the last set containing the values that need to be added to instances of the first 2 sets. If this list is very large you can split it up in pieces and also do this concurrently.