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Creating a Fixed Sized List in Java Using Apache Commons

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Creating a Fixed Sized List in Java Using Apache Commons

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How do you break a Monolith into Microservices at Scale? This ebook shows strategies and techniques for building scalable and resilient microservices.

There are many ways to create a fixed list in Java, one of them is by using the FixedSizeList class, found in the Apache org.apache.commons.collections package ( http://commons.apache.org/collections/). FixedSizeList does not support the add, remove, clear and retain methods and the set method is allowed as far as it doesn’t change the list size:
package fixedsizelist.exemple;

import java.util.Arrays;
import java.util.List;
import org.apache.commons.collections.list.FixedSizeList;

public class FixedSizeListExemple {

    public static void main(String[] args) {

        List fixedList = FixedSizeList.decorate(Arrays.asList(new String[5]));

        fixedList.set(0, "some_name@yahoo.com");
        fixedList.set(1, "some_other_name@gmail.com");
        fixedList.set(2, "777_name@rocketmail.com");
        fixedList.set(3, "bond_007@yahoo.com");
        fixedList.set(4, "james99@yahoo.com");

        System.out.println("\tDisplay list values...\n");
        for (String obj : fixedList) {
            System.out.println(obj.toString());
        }

        try {
            System.out.println("\n\tTrying to modify our fixed list...\n");

            fixedList.add("paul01_mac@yahoo.com");
            fixedList.remove(3);
            fixedList.clear();

        } catch (Exception e) {
          System.out.println
          (" The add, remove, clear and retain operations are unsupported."
          + "\nThe set method is allowed (as it doesn't change the list size).\n");
        }
    }
}


And the output is:

From http://e-blog-java.blogspot.com/2012/02/how-to-create-fixed-list-in-java-using.html

How do you break a Monolith into Microservices at Scale? This ebook shows strategies and techniques for building scalable and resilient microservices.

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