Collections.binarySearch(List, E) in Java

Collections.binarySearch(List, E): This method is available in java.util.Collections class of Java.

Syntax:

<E> int java.util.Collections.binarySearch(List<? extends Comparable<? super E>> list, E key)

This method searches the specified list for the specified object using the binary search algorithm.

Note: The list must be sorted into ascending order according to the natural ordering of its elements

Parameters: Two parameters are required for this method.

list: the list to be searched.

key: the key to be searched for.

Returns: the index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1).

Note: The insertion point is defined as the point at which the key would be inserted into the list.

Exceptions: NA

Approach

Java

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class CollectionsbinarySearch {
    public static void main(String[] args) {

        List<Integer> arrlist = new ArrayList<Integer>();

        arrlist.add(12);
        arrlist.add(14);
        arrlist.add(15);
        arrlist.add(20);

        Integer key = 15;
        System.out.println(Collections.binarySearch(arrlist, 
                                                      key));

    }
}

Output:

2