| 1 | package dmg.util; |
| 2 | |
| 3 | import java.util.Map; |
| 4 | import java.util.List; |
| 5 | import java.util.Set; |
| 6 | import java.util.SortedSet; |
| 7 | import java.util.SortedMap; |
| 8 | import java.util.HashMap; |
| 9 | import java.util.HashSet; |
| 10 | import java.util.TreeMap; |
| 11 | import java.util.TreeSet; |
| 12 | import java.util.ArrayList; |
| 13 | import java.util.concurrent.CopyOnWriteArrayList; |
| 14 | import java.util.concurrent.ConcurrentHashMap; |
| 15 | import java.util.concurrent.BlockingQueue; |
| 16 | import java.util.concurrent.LinkedBlockingQueue; |
| 17 | |
| 18 | /** |
| 19 | * Utility class containing static factory methods for common Java |
| 20 | * collections. Using the factory methods avoids the problem that Java |
| 21 | * does not support type inference for constructors. The following would |
| 22 | * give a compiler warning: |
| 23 | * |
| 24 | * List<String> l = new ArrayList(); |
| 25 | * |
| 26 | * however using the factory method avoids the warning: |
| 27 | * |
| 28 | * List<String> l = CollectionFactory.newArrayList(); |
| 29 | * |
| 30 | * The alternative would be to use: |
| 31 | * |
| 32 | * List<String> l = new ArrayList<String>(); |
| 33 | * |
| 34 | * This does however violate the DRY principle, as the type needs to |
| 35 | * be repeated. |
| 36 | */ |
| 37 | public class CollectionFactory |
| 38 | { |
| 39 | private CollectionFactory() |
| 40 | { |
| 41 | } |
| 42 | |
| 43 | public static <K,V> Map<K,V> newHashMap() |
| 44 | { |
| 45 | return new HashMap<K,V>(); |
| 46 | } |
| 47 | |
| 48 | public static <K,V> SortedMap<K,V> newTreeMap() |
| 49 | { |
| 50 | return new TreeMap<K,V>(); |
| 51 | } |
| 52 | |
| 53 | public static <K,V> Map<K,V> newConcurrentHashMap() |
| 54 | { |
| 55 | return new ConcurrentHashMap<K,V>(); |
| 56 | } |
| 57 | |
| 58 | public static <V> Set<V> newHashSet() |
| 59 | { |
| 60 | return new HashSet<V>(); |
| 61 | } |
| 62 | |
| 63 | public static <V> SortedSet<V> newTreeSet() |
| 64 | { |
| 65 | return new TreeSet<V>(); |
| 66 | } |
| 67 | |
| 68 | public static <V> List<V> newArrayList() |
| 69 | { |
| 70 | return new ArrayList<V>(); |
| 71 | } |
| 72 | |
| 73 | public static <V> List<V> newCopyOnWriteArrayList() |
| 74 | { |
| 75 | return new CopyOnWriteArrayList<V>(); |
| 76 | } |
| 77 | |
| 78 | public static <V> BlockingQueue<V> newLinkedBlockingQueue() |
| 79 | { |
| 80 | return new LinkedBlockingQueue<V>(); |
| 81 | } |
| 82 | } |