Java JDK 二分法 分析demo(推荐)

如下所示：

public class Test{  public static void main(String[] args)  {    Long[] arr = new Long[100000];    for(int i =0;i<100000;i++)    {      arr[i] = (long) i;    }    System.out.println(binarySearch(arr, 3L));        Comparable midVal = (Comparable) 2L;;    System.out.println(midVal.compareTo(2l));  }  private static int binarySearch(Long[] arr, long l)  {    return binarySearch0(arr,0,arr.length,l);  }  private static int binarySearch0(Object[] a, int fromIndex, int toIndex, Object key)  {    int low = fromIndex;    int high = toIndex - 1;    while (low <= high)    {      int mid = (low + high) >>> 1;      Comparable midVal = (Comparable) a[mid];      int cmp = midVal.compareTo(key);      if (cmp < 0)        low = mid + 1;      else if (cmp > 0)        high = mid - 1;      else        return mid; // key found    }    return -(low + 1); // key not found.  }}