二分查找

public class Test {
    public static void main(String[] args) {
        int[] array = {1,2,3,4,5,6,7};
        int value = 8;
        System.out.println(binarySearch(array, value));
    }

    public static int binarySearch(int[] array, int value) {
        int low = 0;
        int high = array.length - 1;
        while (low <= high) {
            int index = (low + high) / 2;
            if (value == array[index]) {
                return index;
            }else if (value < array[index]) {
                high = index - 1;
            } else if (value > array[index]) {
                low = index + 1;
            }
        }
        return -1;
    }
}