标签：his ice style integer 场景 throws param err time()
实例1：
解决问题：如何让n个线程顺序遍历含有n个元素的List集合
import java.util.ArrayList; import java.util.List; import org.apache.commons.lang3.ArrayUtils; public class Test_4 { /** * 多线程处理list * * @param data 数据list * @param threadNum 线程数 */ public synchronized void handleList(List<String> data, int threadNum) { int length = data.size(); int tl = length % threadNum == 0 ? length / threadNum : (length / threadNum + 1); for (int i = 0; i < threadNum; i++) { int end = (i + 1) * tl; HandleThread thread = new HandleThread("线程[" + (i + 1) + "] ", data, i * tl, end > length ? length : end); thread.start(); } } class HandleThread extends Thread { private String threadName; private List<String> data; private int start; private int end; public HandleThread(String threadName, List<String> data, int start, int end) { this.threadName = threadName; this.data = data; this.start = start; this.end = end; } public void run() { List<String> subList = data.subList(start, end)/*.add("^&*")*/; System.out.println(threadName+"处理了"+subList.size()+"条！"); } } public static void main(String[] args) { Test_4 test = new Test_4(); // 准备数据 List<String> data = new ArrayList<String>(); for (int i = 0; i < 6666; i++) { data.add("item" + i); } test.handleList(data, 5); System.out.println(ArrayUtils.toString(data)); } }
实例2：
List多线程并发读取读取现有的list对象
//测试读取List的线程类，大概34秒 package com.thread.list; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; public class Main { public static void main(String[] args) { List<String> list = new ArrayList<String>(); Map<Long,Integer> map = new HashMap<Long,Integer>(); for(int i = 0;i<1000;i++){ list.add(""+i); } int pcount = Runtime.getRuntime().availableProcessors(); long start = System.currentTimeMillis(); for(int i=0;i<pcount;i++){ Thread t = new MyThread1(list,map); map.put(t.getId(),Integer.valueOf(i)); t.start(); try { t.join(); } catch (InterruptedException e) { e.printStackTrace(); } // System.out.println(list.get(i)); } System.out.println("----"+(System.currentTimeMillis() - start)); } } //线程类 package com.thread.list; import java.util.List; import java.util.Map; public class MyThread1 extends Thread { private List<String> list; private Map<Long,Integer> map; public MyThread1(List<String> list,Map<Long,Integer> map){ this.list = list; this.map = map; } @Override public void run() { int pcount = Runtime.getRuntime().availableProcessors(); int i = map.get(Thread.currentThread().getId()); for(;i<list.size();i+=pcount){ System.out.println(list.get(i)); } } }
实例3：
多线程分段处理List集合
场景:大数据List集合,需要对List集合中的数据同标准库中数据进行对比,生成新增,更新,取消数据
解决方案:
newFixedThreadPoolpublic static void main(String[] args) throws Exception { // 开始时间 long start = System.currentTimeMillis(); List<String> list = new ArrayList<String>(); for (int i = 1; i <= 3000; i++) { list.add(i + ""); } // 每500条数据开启一条线程 int threadSize = 500; // 总数据条数 int dataSize = list.size(); // 线程数 int threadNum = dataSize / threadSize + 1; // 定义标记,过滤threadNum为整数 boolean special = dataSize % threadSize == 0; // 创建一个线程池 ExecutorService exec = Executors.newFixedThreadPool(threadNum); // 定义一个任务集合 List<Callable<Integer>> tasks = new ArrayList<Callable<Integer>>(); Callable<Integer> task = null; List<String> cutList = null; // 确定每条线程的数据 for (int i = 0; i < threadNum; i++) { if (i == threadNum - 1) { if (special) { break; } cutList = list.subList(threadSize * i, dataSize); } else { cutList = list.subList(threadSize * i, threadSize * (i + 1)); } // System.out.println("第" + (i + 1) + "组：" + cutList.toString()); final List<String> listStr = cutList; task = new Callable<Integer>() { @Override public Integer call() throws Exception { System.out.println(Thread.currentThread().getName() + "线程：" + listStr); return 1; } }; // 这里提交的任务容器列表和返回的Future列表存在顺序对应的关系 tasks.add(task); } List<Future<Integer>> results = exec.invokeAll(tasks); for (Future<Integer> future : results) { System.out.println(future.get()); } // 关闭线程池 exec.shutdown(); System.out.println("线程任务执行结束"); System.err.println("执行任务消耗了 ：" + (System.currentTimeMillis() - start) + "毫秒"); }
标签：his ice style integer 场景 throws param err time()
原文地址：https://www.cnblogs.com/fanleiyang/p/10523788.html
