Prerequisite: ArrayList in Java Given an ArrayList, the task is to get the first and last element of the ArrayList in Java, Examples:
Input: ArrayList = [1, 2, 3, 4] Output: First = 1, Last = 4 Input: ArrayList = [12, 23, 34, 45, 57, 67, 89] Output: First = 12, Last = 89
Approach:
- Get the ArrayList with elements.
- Get the first element of ArrayList with use of get(index) method by passing index = 0.
- Get the last element of ArrayList with use of get(index) method by passing index = size – 1.
Below is the implementation of the above approach:
Java
// Java code to find first and last element // of ArrayList import java.util.ArrayList;
public class GFG {
// main method
public static void main(String[] args)
{
// creating an Empty Integer ArrayList
ArrayList<Integer> list = new ArrayList<Integer>( 5 );
// using add() to initialize values
list.add( 1 );
list.add( 2 );
list.add( 3 );
list.add( 4 );
// printing initial value ArrayList
System.out.print("ArrayList: " + list);
// find first element
int first = list.get( 0 );
// find last element
int last = list.get(list.size() - 1 );
// print first and last element of ArrayList
System.out.println("\nFirst : " + first
+ ", Last : " + last);
}
} |
Output:
ArrayList: [1, 2, 3, 4] First : 1, Last : 4
Time Complexity: O(1)
Auxiliary Space: O(1)