JAVA 二分查找

package com.session.chop;

import java.util.Arrays;

/**
 * 二分查找
 */
public class BinarySearch {
    public static void main(String[] args) {
        int[] array = new int[]{1, 24, 3, 9, 5, 6, 4, 8};
        Arrays.sort(array);
        System.out.println(binarySearch0(array, 0, 8, 4));
    }

  

    private static int binarySearch0(int[] a, int fromIndex, int toIndex,
                                     int key) {
        int low = fromIndex;
        int high = toIndex - 1;

        while (low <= high) {
            int mid = (low + high) >>> 1;
            int midVal = a[mid];

            if (midVal < key)
                low = mid + 1;
            else if (midVal > key)
                high = mid - 1;
            else
                return mid; // key found
        }
        return -(low + 1);  // key not found.
    }
}