How To Reverse A List In Java

Chapter: Miscellaneous Last Updated: 17-05-2023 15:04:05 UTC

Program:

            /* ............... START ............... */
                import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class ReverseListExample {
    public static void main(String[] args) {
        // Create a list
        List<Integer> numbers = new ArrayList<>();
        numbers.add(1);
        numbers.add(2);
        numbers.add(3);
        numbers.add(4);
        numbers.add(5);

        // Print the original list
        System.out.println("Original list: " + numbers);

        // Reverse the list
        Collections.reverse(numbers);

        // Print the reversed list
        System.out.println("Reversed list: " + numbers);
    }
}

                /* ............... END ............... */
        

Output

Original list: [1, 2, 3, 4, 5]
Reversed list: [5, 4, 3, 2, 1]

Notes:

• First, we create an ArrayList called numbers and add some integer values to it. In this example, we added the numbers 1, 2, 3, 4, and 5 to the list.
• Then, we print the original list using System.out.println(), which displays the list as [1, 2, 3, 4, 5].
• Next, we use the Collections.reverse() method to reverse the order of elements in the numbers list. This method modifies the original list in-place, meaning it doesn't create a new reversed list but changes the existing list itself.
• After reversing the list, we print the reversed list using System.out.println(). The reversed list is displayed as [5, 4, 3, 2, 1].
• So, the program demonstrates how to use the Collections.reverse() method to reverse the order of elements in a list in Java.

Tags

How to reverse a list in Java using for loop # Java program to reverse a list # Java Collections reverse

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