计算很大数组中List的和
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package thread;import java.util.Iterator;import java.util.Random;import java.util.concurrent.BrokenBarrierException;import java.util.concurrent.ConcurrentLinkedQueue;import java.util.concurrent.CyclicBarrier;public class SegmentCount {public static void main(String[] args) {int[] arr = new int[10123];Random ran = new Random();int sum = 0;for (int i = 0; i < arr.length; i++) {arr[i] = ran.nextInt(10000);sum += arr[i];}System.out.println("结果应该为：" + sum);// 多线程进行数组拆分计算int threadSize = 10;int avg = arr.length / threadSize;// 平均任务数int surplus = arr.length % threadSize;// 剩余任务数threadSize = surplus > 0 ? (++threadSize) : threadSize;final ConcurrentLinkedQueue<Integer> queue = new ConcurrentLinkedQueue<Integer>();// 结果队列CyclicBarrier barrier = new CyclicBarrier(threadSize, new Runnable() {public void run() {System.out.println("统计:");System.out.println(queue);int sum = 0;Iterator<Integer> it = queue.iterator();while (it.hasNext()) {sum += Integer.valueOf(it.next().toString());}System.out.println("sum:" + sum);}});for (int i = 1; i <= threadSize; i++) {int end = i * avg;end = (end > arr.length) ? arr.length : end;new Thread(new Segment(barrier, arr, (i - 1) * avg, end, queue)).start();}}}class Segment implements Runnable {CyclicBarrier barrier;int[] arr;int start;int end;ConcurrentLinkedQueue<Integer> queue;public Segment(CyclicBarrier barrier, int[] arr, int start, int end,ConcurrentLinkedQueue<Integer> queue) {super();this.barrier = barrier;this.arr = arr;this.start = start;this.end = end;this.queue = queue;}int sum = 0;public void run() {System.out.println(Thread.currentThread().getName() + ",start:" + start+ ",end:" + end);for (int i = start; i < end; i++) {sum += arr[i];}queue.offer(sum);try {barrier.await();} catch (InterruptedException e) {e.printStackTrace();} catch (BrokenBarrierException e) {e.printStackTrace();}}}package thread;import java.util.ArrayList;import java.util.List;import java.util.Random;import java.util.concurrent.Callable;import java.util.concurrent.ConcurrentLinkedQueue;import java.util.concurrent.ExecutionException;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Future;import java.util.concurrent.FutureTask;public class SegmentCount2 {public static void main(String[] args) throws InterruptedException,ExecutionException {int[] arr = new int[10123];Random ran = new Random();int sum = 0;for (int i = 0; i < arr.length; i++) {arr[i] = ran.nextInt(10000);sum += arr[i];}System.out.println("结果应该为：" + sum);// 多线程进行数组拆分计算int threadSize = 10;int avg = arr.length / threadSize;// 平均任务数int surplus = arr.length % threadSize;// 剩余任务数threadSize = surplus > 0 ? (++threadSize) : threadSize;ExecutorService pool = Executors.newCachedThreadPool();List<Segment2> tasks = new ArrayList<Segment2>();for (int i = 1; i <= threadSize; i++) {int end = i * avg;end = (end > arr.length) ? arr.length : end;tasks.add(new Segment2(arr, (i - 1) * avg, end));}// 执行给定的任务，当所有任务完成时，返回保持任务状态和结果的 Future 列表。List<Future<Integer>> result = pool.invokeAll(tasks);int summ = 0;for (int i = 0; i < result.size(); i++) {FutureTask<Integer> task = (FutureTask<Integer>) result.get(i);summ += Integer.valueOf(task.get().toString());}System.out.println("总共：" + summ);pool.shutdown();}}class Segment2 implements Callable<Integer> {int[] arr;int start;int end;public Segment2(int[] arr, int start, int end) {super();this.arr = arr;this.start = start;this.end = end;}int sum = 0;public Integer call() throws Exception {System.out.println(Thread.currentThread().getName() + ",start:" + start+ ",end:" + end);for (int i = start; i < end; i++) {sum += arr[i];}return sum;}}package thread;import java.util.Iterator;import java.util.Random;import java.util.concurrent.ConcurrentLinkedQueue;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutionException;public class SegmentCount3 {public static void main(String[] args) throws InterruptedException,ExecutionException {int[] arr = new int[10123];Random ran = new Random();int sum = 0;for (int i = 0; i < arr.length; i++) {arr[i] = ran.nextInt(10000);sum += arr[i];}System.out.println("结果应该为：" + sum);// 多线程进行数组拆分计算int threadSize = 10;int avg = arr.length / threadSize;// 平均任务数int surplus = arr.length % threadSize;// 剩余任务数threadSize = surplus > 0 ? (++threadSize) : threadSize;final ConcurrentLinkedQueue<Integer> queue = new ConcurrentLinkedQueue<Integer>();// 结果队列CountDownLatch beginSignal = new CountDownLatch(1);CountDownLatch endSignal = new CountDownLatch(threadSize);for (int i = 1; i <= threadSize; i++) {int end = i * avg;end = (end > arr.length) ? arr.length : end;new Thread(new Segment3(beginSignal, endSignal, arr, (i - 1) * avg,end, queue)).start();}System.out.println("开闸");beginSignal.countDown();endSignal.await();System.out.println("统计：" + queue);Iterator<Integer> it = queue.iterator();int summ = 0;while (it.hasNext()) {summ += it.next();}System.out.println(summ);}}class Segment3 implements Runnable {CountDownLatch beginSignal;CountDownLatch endSignal;int[] arr;int start;int end;ConcurrentLinkedQueue<Integer> queue;public Segment3(CountDownLatch beginSignal, CountDownLatch endSignal,int[] arr, int start, int end, ConcurrentLinkedQueue<Integer> queue) {super();this.beginSignal = beginSignal;this.endSignal = endSignal;this.arr = arr;this.start = start;this.end = end;this.queue = queue;}int sum = 0;public void run() {try {beginSignal.await();System.out.println(Thread.currentThread().getName() + ",start:"+ start + ",end:" + end);for (int i = start; i < end; i++) {sum += arr[i];}queue.offer(sum);endSignal.countDown();} catch (InterruptedException e) {e.printStackTrace();}}}