[참고] 이진탐색

public class BinarySearch {
    public static void main(String[] args) {
        int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
 
        binarySearch(2, arr);
    }
 
    public static void binarySearch(int iKey, int arr[]) {
        int mid;
        int left = 0;
        int right = arr.length - 1;
 
        while (right >= left) {
            mid = (right + left) / 2;
 
            if (iKey == arr[mid]) {
                System.out.println(iKey + " is in the array with index value: " + mid);
                break;
            }
 
            if (iKey < arr[mid]) {
                right = mid - 1;
            } else {
                left = mid + 1;
            }
 
        }
    }
}