forkjoin实现的归并排序

forkjoin实现的归并排序

import java.util.Arrays;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;

/**
 * forkjoin实现的归并排序
 */
public class FkSort {


    private static class SumTask extends RecursiveTask<int[]>{

        private final static int THRESHOLD = 16;
        private int[] src;

        public SumTask(int[] src) {
            this.src = src;
        }

        @Override
        protected int[] compute() {
            if(src.length <= THRESHOLD){
                return InsertionSort.sort(src);
            }else{
                //fromIndex....mid.....toIndex
                int mid = src.length / 2;
                SumTask leftTask = new SumTask(Arrays.copyOfRange(src, 0, mid));
                SumTask rightTask = new SumTask(Arrays.copyOfRange(src, mid, src.length));
                invokeAll(leftTask,rightTask);
                int[] leftResult = leftTask.join();
                int[] rightResult = rightTask.join();
                return MergeSort.merge(leftResult,rightResult);
            }
        }
    }


    public static void main(String[] args) {

        ForkJoinPool pool = new ForkJoinPool();
        int[] src = MakeArray.makeArray();

        SumTask innerFind = new SumTask(src);

        long start = System.currentTimeMillis();

        int[] invoke = pool.invoke(innerFind);
//        for(int number:invoke){
//            System.out.println(number);
//        }
        System.out.println(" spend time:"+(System.currentTimeMillis()-start)+"ms");

    }


 public class MakeArray {
    //数组长度
    public static final int ARRAY_LENGTH  = 40000000;
    public final static int THRESHOLD = 47;
 
    public static int[] makeArray() {
 
        //new一个随机数发生器
        Random r = new Random();
        int[] result = new int[ARRAY_LENGTH];
        for(int i=0;i<ARRAY_LENGTH;i++){
            //用随机数填充数组
            result[i] =  r.nextInt(ARRAY_LENGTH*3);
        }
        return result;
 
    }
}


}

标签：src,归并,java,int,private,import,排序,forkjoin
来源： https://blog.51cto.com/u_15193673/2850029