java 多线程处理一个list的集合

Posted 2022-06-20 孟令杰

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class App 
	public static final String module = App.class.getName();

	public static void main(String[] args) 

		try 
			List<String> list = new ArrayList<>();
			for (int i = 0; i < 100; i++) 
				list.add(i + ",");
			

			System.out.println(new App().list2Str(list, 5));
		 catch (Exception e) 
			e.printStackTrace();
		
	
	public String list2Str(List<String> list, final int nThreads)
			throws Exception 
		if (list == null || list.isEmpty()) 
			return null;
		
		StringBuffer ret = new StringBuffer();

		int size = list.size();
		ExecutorService executorService = Executors.newFixedThreadPool(nThreads);
		List<Future<String>> futures = new ArrayList<Future<String>>(nThreads);
		for (int i = 0; i < nThreads; i++) 
			final List<String> subList = list.subList(size / nThreads * i, size/ nThreads * (i + 1));
			Callable<String> task = new Callable<String>() 
				@Override
				public String call() throws Exception 
					StringBuffer sb = new StringBuffer();
					for (String str : subList) 
						sb.append(str);
					
					return sb.toString();
				
			;
			futures.add(executorService.submit(task));
		

		for (Future<String> future : futures) 
			ret.append(future.get());
		
		executorService.shutdown();

		return ret.toString();
	<span id="transmark"></span>

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