How to get the last value of an ArrayList in java.

There are multiple way to get the last value of an ArrayList in java.

Using reduce() method :-

In Java, reduce() is a method of the Stream interface.
In that stream, the first argument to the operator must return the value of the previous application and the second argument must return the current stream element.
There are second element is fetch last element from lambda expression and return in optional.
ifPresent() method check value is not null and print the last element.

Using list.size() method :-

The size() method of the List interface in java is used to get the number of elements in this list.
isEmpty() method check list is empty or not.
If it is empty then return null value.
If it not empty then list.size()-1 give the index position of last element.
get() method use this index value and print the last value.

Syntax: public int size()

Using get() method :-

There also use reduce() method of Stream interface.
In that stream, the first argument to the operator must return the value of the previous application and the second argument must return the current stream element.
There are second element is fetch last element.
From get() method we pick the last value and print element.

				
					import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

public class LastElement {
	public static void main(String[] args) {
		List<Integer> list = new ArrayList<Integer>();
		list.add(4);
		list.add(5);
		list.add(6);

		// from optional and reduce method
		System.out.println("from optional and reduce method the last element are :- ");
		Optional last = list.stream().reduce((first, second) -> second);
		last.ifPresent(System.out::println);

		// from list.size() method
		Object lastElement = list.isEmpty() ? null : list.get(list.size() - 1);
		System.out.println("from list.size() method the last element are :- " + lastElement);

		// from reduce and get method
		System.out.println("from reduce and get method the last element are :- ");
		Integer element = list.stream().reduce((first, second) -> second).get();
		System.out.println(element);
	}
}

Output :-
from optional and reduce method the last element are :-
6
from list.size() method the last element are :- 6
from reduce and get method the last element are :-
6