Java 8 – Find First and Last elements in a List or ArrayList ?

In this article, we will discuss how to get First and Last elements from a List or an ArrayList using Java 8 Streams API

Find First and Last elements in an ArrayList

  1. Using Java 8 Streams API
  2. Before Java 8 release

1. Using Java 8 Streams API

FindFirstAndLastElementInArrayListInJava8.java

package in.bench.resources.find.list;

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

public class FindFirstAndLastElementInArrayListInJava8 {

	public static void main(String[] args) {

		// local variables
		String first = null;
		String last = null;


		// create List object
		List<String> names = new ArrayList<>();


		// add names to newly created ArrayList
		names.add("Deepinder Goyal");
		names.add("Vinay Sanghi");
		names.add("Bipin Preet Singh");
		names.add("Vijay Shekhar Sharma");
		names.add("Falguni Nayar");


		// findFirst() - find First element in ArrayList
		first = names.stream().findFirst().get();


		// reduce() - find Last element in ArrayList
		last = names.stream().reduce((one, two) -> two).get();


		// print to console
		System.out.println("First name in the List is = " + first);
		System.out.println("Last name in the List is = " + last);
	}
}

Output:

First name in the List is = Deepinder Goyal
Last name in the List is = Falguni Nayar

2. Before Java 8 Release

  • To find first and last elements in an ArrayList, check whether list is empty
  • If list is not empty, then
    • get first element using get(index) method by passing 0th index
    • get last element using get(index) method by passing last index of the list i.e., (list.size -1)

FindFirstAndLastElementInArrayList.java

package in.bench.resources.find.list;

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

public class FindFirstAndLastElementInArrayList {

	public static void main(String[] args) {

		// local variables
		String first = null;
		String last = null;


		// create List object
		List<String> names = new ArrayList<>();


		// add names to newly created ArrayList
		names.add("Deepinder Goyal");
		names.add("Vinay Sanghi");
		names.add("Bipin Preet Singh");
		names.add("Vijay Shekhar Sharma");
		names.add("Falguni Nayar");


		// find First and Last element of ArrayList
		if(!names.isEmpty()) {

			first = names.get(0);
			last = names.get(names.size() - 1);
		}


		// print to console
		System.out.println("First name in the List is = " + first);
		System.out.println("Last name in the List is = " + last);
	}
}

Output:

First name in the List is = Deepinder Goyal
Last name in the List is = Falguni Nayar

Related Articles:

References:

Happy Coding !!
Happy Learning !!

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