Java Collection How to - Reverse an unmodifiable List

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Question

We would like to know how to reverse an unmodifiable List.

Answer

import java.util.AbstractList;
import java.util.Arrays;
import java.util.List;
/*from   w w w.  ja  va  2  s. c o m*/
public class Main
{
    public static void main(String[] args)
    {
        String[] array = {"A","B","C","D","E"};

        List<String> list = Arrays.asList(array);
        System.out.println("List         : "+list);

        List<String> reversedView = reversedView(list);
        System.out.println("Reversed view: "+reversedView);
    }

    public static <T> List<T> reversedView(final List<T> list)
    {
        return new AbstractList<T>()
        {
            @Override
            public T get(int index)
            {
                return list.get(list.size()-1-index);
            }

            @Override
            public int size()
            {
                return list.size();
            }
        };
    }
}

The code above generates the following result.

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