二分查找的对象是一个有序的数组，可以使用递归和非递归两种方式实现。

public class Test {
    public static void main(String[] args) {
       int [] array= {1,2,3,4,5,6,7,8,9,10,11,12};
        int addr = binarySearch(array,7);
        System.out.println(addr);
        int sort = recursionSearch(array, 7, 0, array.length);
        System.out.println(sort);

    }



    private static int binarySearch(int [] array,int keyword){
        int left = 0;
        int right = array.length;
        int middle = 0;
        if(right==0){
            return -1;
        }
        while(left<right){
            middle = (left+right)/2;
            if(array[middle]==keyword){
                return middle+1;
            }else if(array[middle]>keyword){
                right = middle+1;
            }else {
                left = middle-1;
            }

        }
        return -1;

    }

    private static int recursionSearch(int [] array,int keyword,int left,int right){//递归实现
        if(left<=right){
            int middle = (left+right)/2;
            if(keyword==array[middle]){
                return middle+1;
            }else if(keyword>array[middle]){
                return recursionSearch(array,keyword,middle+1,right);
            }else {
                return recursionSearch(array,keyword,left,middle-1);
            }
        }
        return -1;
    }
}