How to Reverse a List in Java - Step by Step Examples

How to Reverse a List in Java ?

Answer

To reverse a list in Java, you can use the built-in Collections.reverse() method or manually reverse the list by iterating over it and swapping elements from both ends.

✐ Examples

1 Reverse a List using Collections.reverse() Method

In this example,

We have a list named originalList containing elements in the original order.
We use the Collections.reverse() method to reverse the list in-place.

Java Program

import java.util.*;

public class Main {
    public static void main(String[] args) {
        List<Integer> originalList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));
        Collections.reverse(originalList);
        System.out.println("Reversed list: " + originalList);
    }
}

Output

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

2 Manually Reversing the List

In this example,

We have a list named originalList containing elements in the original order.
We iterate over the list using two pointers, one starting from the beginning and the other from the end.
We swap elements from both ends until the pointers meet at the middle of the list.

Java Program

import java.util.*;

public class Main {
    public static void main(String[] args) {
        List<Integer> originalList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));
        int start = 0;
        int end = originalList.size() - 1;
        while (start < end) {
            int temp = originalList.get(start);
            originalList.set(start, originalList.get(end));
            originalList.set(end, temp);
            start++;
            end--;
        }
        System.out.println("Reversed list: " + originalList);
    }
}

Output

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

Summary

In this tutorial, we learned How to Reverse a List in Java language with well detailed examples.

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How to Reverse a List in Java - Step by Step Examples

How to Reverse a List in Java ?

Answer

✐ Examples

1 Reverse a List using Collections.reverse() Method

Java Program

Output

2 Manually Reversing the List

Java Program

Output

Summary

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