Finding and Accessing elements in a List

FindingElementInList.java

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

public class FindingElementInList {
    public static void main(String[] args) {
        List<Integer> list1 = new ArrayList<>(List.of(6, 1, 2, 3, 4, 5, 6));
        List<Integer> list2 = new ArrayList<>(List.of(1, 2, 3));

        // output: contains 1: true
        System.out.println("contains 1: " + list1.contains(1));

        /*
         output: list1 contains list2: true
         Note: use HashSet if you want to check only unique elements
         System.out.println(new HashSet<>(list1).containsAll(list2));
         */
        System.out.println("list1 contains list2: " + list1.containsAll(list2));

        // this prints false because obviously list2 doesn't contain all elements in list1
        System.out.println(list2.contains(list1));

        //output: first index of 6: 0
        System.out.println("first index of 6: " + list1.indexOf(6));

        // prints -1 because list1 doesn't contain 99
        System.out.println(list1.indexOf(99));

        // lastIndexOf will search the list from end to the back
        // output: last index of 6: 6
        System.out.println("last index of 6: " + list1.lastIndexOf(6));

        // Output: the element at index 2 is: 3
        System.out.println("the element at index 2 is: " + list2.get(2));

        // list 2 has only 3 element and the last index is 2
        // this line throws IndexOutOfBoundsException as index 8 is out of bounds
        //System.out.println(list2.get(8));


        System.out.println(list1.isEmpty()); // false
        System.out.println(list1.size()); // 7
        list1.clear(); // emptying list
        System.out.println(list1.isEmpty()); // true
        System.out.println(list1.size()); // 0
    }
}