Binary Search a non-existing number in a sorted array, return a larger negative number than -1 - arrays

Question

When the search number is 12, why does it return -6 instead of -1?
int[] list = {2, 4, 7, 10, 11, 45, 50, 59, 60, 66, 69, 70, 79};
System.out.println("1. Index is " + Arrays.binarySearch(list, 11));
System.out.println("2. Index is " + Arrays.binarySearch(list, 12));
Result:
1. Index is 4
2. Index is -6
Update
Now I understand because
Arrays.binarySearch will return
(-(insertion point) - 1)
if the number is not in the array.
i.e
12 is at insertion of 5, so return (-(5) - 1) = -6.
Thanks for the help.

Answer 1

You may refer to the Javadoc : Arrays.binarySearch(int[] a,int key)
It returns :
index of the search key, if it is contained in the array;
otherwise : (-(insertion point) - 1).
Here the insertion point would be :
int[] list = {2, 4, 7, 10, 11, 45, 50, 59, 60, 66, 69, 70, 79};
// 1^ 2^ 3^ 4^ 5^
The position 5 so (-5-1) = -6

Answer 2

Extracted from BinarySearch
Return value:
This method returns index of the search key, if it is contained in the array, else it returns (-(insertion point) - 1). The insertion point is the point at which the key would be inserted into the array: the index of the first element greater than the key, or a.length if all elements in the array are less than the specified key.
From the return value explanation, it returns the negation of the position the element will be in the array (that is -5) minus 1, which would be -6.

Answer 3

This is a common return type for BinarySearch() methods.
If you would like to print the index of an integer a :
int[] list = {2, 4, 7, 10, 11, 45, 50, 59, 60, 66, 69, 70, 79};
int a =12; //Value can be updated or read through Scanner
int temp = Arrays.binarySearch(list,a);
if(temp>=0){
System.out.println("Index of a is : " + temp)
}else{
System.out.println("Insertion point for a is : " + (-1)*(temp+1);
}