Java Thread - 如何搜索數(shù)組與未來

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 Main {
  public static long pmax(final long[][] arr, int numThreads) {
    ExecutorService pool = Executors.newFixedThreadPool(numThreads);
    try {
      List<Future<Long>> list = new ArrayList<Future<Long>>();
      for (int i = 0; i < arr.length; i++) {
        final long[] subArr = arr[i];
        list.add(pool.submit(new Callable<Long>() {
          public Long call() {
            long max = Long.MIN_VALUE;
            for (int j = 0; j < subArr.length; j++) {
              if (subArr[j] > max) {
                max = subArr[j];
              }
            }
            return max;
          }
        }));
      }
      // find the max of each slice's max:
      long max = Long.MIN_VALUE;
      for (Future<Long> future : list) {
        long threadMax = future.get();
        System.out.println("threadMax: " + threadMax);
        if (threadMax > max) {
          max = threadMax;
        }
      }
      return max;
    } catch (Exception e) {
      System.out.println(e);
      return -1;
    } finally {
      pool.shutdown();
    }
  }

  public static void main(String args[]) {
    long[][] data = new long[1000][1000];
    for (int i = 0; i < 1000; i++) {
      for (int j = 0; j < 1000; j++) {
        data[i][j] = i*j*j;
      }
    }
    int numThreads = 32;
    long pmax = pmax(data, numThreads);
    System.out.println("pmax: " + pmax);
  }
}