BinarySearch.java

public class BinarySearch {
    public static void main(String[] args) {
        int[] array = {1, 3, 5, 6};
        System.out.println(binarySearch(array, 6));
    }

    // Returns the 0-based index of the key element
    // Returns -1 if not found
    public static int binarySearch(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;

        while (left <= right) {
            // Computing the average with overflow protection
            int mid = left + (right - left) / 2;

            if (array[mid] == key) {
                return mid;
            } else if (array[mid] < key) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }

        return -1;
    }
}