java arraylist get second largest value

To get the second largest value in an ArrayList in Java, you can first sort the list using the sort() method of the Collections class, and then get the element at index list.size() - 2.

Here is an example of how to get the second largest value in an ArrayList of integers:

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

public class ArrayListSecondLargestExample {

    public static void main(String[] args) {
        ArrayList<Integer> numbers = new ArrayList<>();
        numbers.add(5);
        numbers.add(2);
        numbers.add(7);
        numbers.add(1);
        numbers.add(3);
        numbers.add(6);
        numbers.add(4);

        Collections.sort(numbers);

        int secondLargest = numbers.get(numbers.size() - 2);

        System.out.println("Second largest: " + secondLargest);
    }
}

This code creates an ArrayList of integers called numbers and adds some elements to it. It then sorts the list using the sort() method of the Collections class, which sorts the elements in ascending order according to their natural ordering.

After sorting the list, the code gets the element at index numbers.size() - 2, which is the second largest element in the list. It assigns this value to the secondLargest variable and prints it to the console.

Note that the sort() method uses the Comparable interface to determine the natural ordering of the elements. If the elements in the ArrayList are not comparable, or if you want to specify a custom sorting order, you can use the sort() method with a comparator.

For example, to sort the elements in descending order, you can use a comparator that compares the elements in reverse order:

Collections.sort(numbers, Collections.reverseOrder());

This code sorts the numbers list in descending order using the reverseOrder() comparator provided by the Collections class. The second largest element will now be at index 1 in the sorted list.