binary search implementation using java collections

1// Java implementation of iterative Binary Search 
2class BinarySearch { 
3	// Returns index of x if it is present in arr[], 
4	// else return -1 
5	int binarySearch(int arr[], int x) 
6	{ 
7		int l = 0, r = arr.length - 1; 
8		while (l <= r) { 
9			int m = l + (r - l) / 2; 
10
11			// Check if x is present at mid 
12			if (arr[m] == x) 
13				return m; 
14
15			// If x greater, ignore left half 
16			if (arr[m] < x) 
17				l = m + 1; 
18
19			// If x is smaller, ignore right half 
20			else
21				r = m - 1; 
22		} 
23
24		// if we reach here, then element was 
25		// not present 
26		return -1; 
27	} 
28
29	// Driver method to test above 
30	public static void main(String args[]) 
31	{ 
32		BinarySearch ob = new BinarySearch(); 
33		int arr[] = { 2, 3, 4, 10, 40 }; 
34		int n = arr.length; 
35		int x = 10; 
36		int result = ob.binarySearch(arr, x); 
37		if (result == -1) 
38			System.out.println("Element not present"); 
39		else
40			System.out.println("Element found at "
41							+ "index " + result); 
42	} 
43} 

1public int runBinarySearchRecursively(
2  int[] sortedArray, int key, int low, int high) {
3    int middle = (low + high) / 2;
4        
5    if (high < low) {
6        return -1;
7    }
8
9    if (key == sortedArray[middle]) {
10        return middle;
11    } else if (key < sortedArray[middle]) {
12        return runBinarySearchRecursively(
13          sortedArray, key, low, middle - 1);
14    } else {
15        return runBinarySearchRecursively(
16          sortedArray, key, middle + 1, high);
17    }
18}
19

1// Returns index of key in sorted list sorted in
2// ascending order
3public static int binarySearch(List slist, T key)
4
5// Returns index of key in sorted list sorted in
6// order defined by Comparator c.
7public static int binarySearch(List slist, T key, Comparator c)
8
9If key is not present, the it returns "(-(insertion point) - 1)". 
10The insertion point is defined as the point at which the key 
11would be inserted into the list.