Re: Using Java Classes to Sort a Small Array Quickly

Robert Klemme <>
Thu, 01 Sep 2011 08:32:26 +0200
On 01.09.2011 04:48, KevinSimonson wrote:

I have an<enum> named<ProjectEnum> that has twelve values. Today I
added an instance variable to it, a<String> named<collectionTitle>.
The engineer I'm working with asked me to write a static method in
class<ProjectEnum> that returns an array of<ProjectEnum>s sorted
alphabetically by this value<collectionTitle>.

Since we're talking about an enum and I am sure you made field "name"
final (i.e. to make instances immutable) you can completely ignore sort
performance. You just need to sort once. For example:

package en;

import java.util.Arrays;
import java.util.Comparator;

public enum ProjectEnum {

   P1("xyz"), P2("abc"), P3("def");

   private final String collectionTitle;

   private ProjectEnum(String name) {
     if (name == null) {
       throw new NullPointerException();

     this.collectionTitle = name;

   public String getCollectionTitle() {
     return collectionTitle;

   private static final ProjectEnum[] sortedValues;

   static {
     sortedValues = ProjectEnum.values();

     Arrays.sort(sortedValues, new Comparator<ProjectEnum>() {
       public int compare(ProjectEnum o1, ProjectEnum o2) {
         return o1.getCollectionTitle().compareTo(o2.getCollectionTitle());

   public static ProjectEnum[] sorted() {
     return Arrays.copyOf(sortedValues, sortedValues.length);

Kind regards


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