BinarySearch.java

package binary_search;

import java.util.ArrayList;

// 18.5 Алгоритм бинарного поиска
// Task 18.1.3
public class BinarySearch {

    private ArrayList<String> list;

    public BinarySearch(ArrayList<String> list) {
        this.list = list;
    }

    public int search(String query) {
        return search(query, 0, list.size() - 1);
    }

    private int search(String query, int from, int to) {
        if (to < from) {
            return -1;
        }
//        int middle = (from + to) / 2;
        int middle = from + (to - from) / 2;

        int comparison = query.compareTo(list.get(middle));

        if (comparison == 0) {
            return middle;
        }
        if (comparison > 0) {
            return search(query, middle + 1, to);
        }
        return search(query, from, middle - 1);
    }
}