Search Insert Position

public class Solution {
    public int searchInsert(int[] A, int target) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(A.length == 0) return 0;
        else if(A.length == 1)
        {
            if(target == A[0] || target < A[0]) return 0;
            else return 1;
        }
        else return check(A, 0, A.length-1, target);
    }
    private int check(int[] A, int left, int right, int target)  //binary search
    {
        int mid = (int)Math.floor((left+right)/2);
        if(A[mid] == target) return mid;
        else if((right-left) == 1)     //cannot find the target after search the entire array
        {
            if(target>A[right]) return right+1;      //insert the target before the right element
            else if(target<A[left])
            {
                if((left-1)>0) return left-1;    //insert before the left element
                else return 0;        //insert at the begining
            }
            else return right;   //insert btween left and right
        }
        else{
            if(target>A[mid]) return check(A, mid, right, target);
            else return check(A, left, mid, target);
        }
    }
}