Java Language
Alternatieve collecties

Opmerkingen

Apache HashBag, Guava HashMultiset en Eclipse HashBag

Een tas / ultiset slaat elk object in de collectie op samen met een aantal gebeurtenissen. Met extra methoden op de interface kunnen meerdere exemplaren van een object tegelijk worden toegevoegd of verwijderd. JDK analog is HashMap <T, Integer>, wanneer waarden het aantal exemplaren van deze sleutel is.

Voorbeelden :

1. Met behulp van SynchronizedSortedBag van Apache :

    // Parse text to separate words
    String INPUT_TEXT = "Hello World! Hello All! Hi World!";
    // Create Multiset
    Bag bag = SynchronizedSortedBag.synchronizedBag(new TreeBag(Arrays.asList(INPUT_TEXT.split(" "))));

    // Print count words
    System.out.println(bag); // print [1:All!,2:Hello,1:Hi,2:World!]- in natural (alphabet) order
    // Print all unique words
    System.out.println(bag.uniqueSet());    // print [All!, Hello, Hi, World!]- in natural (alphabet) order


    // Print count occurrences of words
    System.out.println("Hello = " + bag.getCount("Hello"));    // print 2
    System.out.println("World = " + bag.getCount("World!"));    // print 2
    System.out.println("All = " + bag.getCount("All!"));    // print 1
    System.out.println("Hi = " + bag.getCount("Hi"));    // print 1
    System.out.println("Empty = " + bag.getCount("Empty"));    // print 0

    // Print count all words
    System.out.println(bag.size());    //print 6

    // Print count unique words
    System.out.println(bag.uniqueSet().size());    //print 4

2. TreeBag van Eclipse (GC) gebruiken :

    // Parse text to separate words
    String INPUT_TEXT = "Hello World! Hello All! Hi World!";
    // Create Multiset
    MutableSortedBag<String> bag =  TreeBag.newBag(Arrays.asList(INPUT_TEXT.split(" ")));

    // Print count words
    System.out.println(bag); // print [All!, Hello, Hello, Hi, World!, World!]- in natural order
    // Print all unique words
    System.out.println(bag.toSortedSet());    // print [All!, Hello, Hi, World!]- in natural order

    // Print count occurrences of words
    System.out.println("Hello = " + bag.occurrencesOf("Hello"));    // print 2
    System.out.println("World = " + bag.occurrencesOf("World!"));    // print 2
    System.out.println("All = " + bag.occurrencesOf("All!"));    // print 1
    System.out.println("Hi = " + bag.occurrencesOf("Hi"));    // print 1
    System.out.println("Empty = " + bag.occurrencesOf("Empty"));    // print 0

    // Print count all words
    System.out.println(bag.size());    //print 6

    // Print count unique words
    System.out.println(bag.toSet().size());    //print 4

3. LinkedHashMultiset van Guava gebruiken :

    // Parse text to separate words
    String INPUT_TEXT = "Hello World! Hello All! Hi World!";
    // Create Multiset
    Multiset<String> multiset = LinkedHashMultiset.create(Arrays.asList(INPUT_TEXT.split(" ")));

    // Print count words
    System.out.println(multiset); // print [Hello x 2, World! x 2, All!, Hi]- in predictable iteration order
    // Print all unique words
    System.out.println(multiset.elementSet());    // print [Hello, World!, All!, Hi] - in predictable iteration order

    // Print count occurrences of words
    System.out.println("Hello = " + multiset.count("Hello"));    // print 2
    System.out.println("World = " + multiset.count("World!"));    // print 2
    System.out.println("All = " + multiset.count("All!"));    // print 1
    System.out.println("Hi = " + multiset.count("Hi"));    // print 1
    System.out.println("Empty = " + multiset.count("Empty"));    // print 0

    // Print count all words
    System.out.println(multiset.size());    //print 6

    // Print count unique words
    System.out.println(multiset.elementSet().size());    //print 4

Meer voorbeelden:

I. Apache-verzameling:

1. HashBag - bestelling niet gedefinieerd
2. SynchronizedBag - gelijktijdig en volgorde niet gedefinieerd
3. SynchronizedSortedBag - - gelijktijdige en gesorteerde volgorde
4. TreeBag - gesorteerde volgorde

II. GS / Eclipse-collectie

5. MutableBag - volgorde niet gedefinieerd
6. MutableSortedBag - gesorteerde volgorde

III. guava

7. HashMultiset - volgorde niet gedefinieerd
8. TreeMultiset - gesorteerde volgorde
9. LinkedHashMultiset - invoegvolgorde
10. ConcurrentHashMultiset - gelijktijdig en volgorde niet gedefinieerd

Multimap in Guava-, Apache- en Eclipse-collecties

Met deze multimap zijn dubbele sleutel / waarde-paren mogelijk. JDK-analogen zijn HashMap <K, List>, HashMap <K, Set> enzovoort.

Taak : Parse "Hallo wereld! Hallo allemaal! Hallo wereld!" tekenreeks om woorden te scheiden en alle indexen van elk woord af te drukken met behulp van MultiMap (bijvoorbeeld Hello = [0, 2], World! = [1, 5] enzovoort)

1. MultiValueMap van Apache

    String INPUT_TEXT = "Hello World! Hello All! Hi World!";
    // Parse text to words and index
    List<String> words = Arrays.asList(INPUT_TEXT.split(" "));
    // Create Multimap
    MultiMap<String, Integer> multiMap = new MultiValueMap<String, Integer>();


    // Fill Multimap
    int i = 0;
    for(String word: words) {
        multiMap.put(word, i);
        i++;
    }

    // Print all words
    System.out.println(multiMap); // print {Hi=[4], Hello=[0, 2], World!=[1, 5], All!=[3]} - in random orders
    // Print all unique words
    System.out.println(multiMap.keySet());    // print [Hi, Hello, World!, All!] - in random orders

    // Print all indexes
    System.out.println("Hello = " + multiMap.get("Hello"));    // print [0, 2]
    System.out.println("World = " + multiMap.get("World!"));    // print [1, 5]
    System.out.println("All = " + multiMap.get("All!"));    // print [3]
    System.out.println("Hi = " + multiMap.get("Hi"));    // print [4]
    System.out.println("Empty = " + multiMap.get("Empty"));    // print null

    // Print count unique words
    System.out.println(multiMap.keySet().size());    //print 4

2. HashBiMap van GS / Eclipse-collectie

    String[] englishWords = {"one", "two", "three","ball","snow"};
    String[] russianWords = {"jeden", "dwa", "trzy", "kula", "snieg"};

    // Create Multiset
    MutableBiMap<String, String> biMap = new HashBiMap(englishWords.length);
    // Create English-Polish dictionary
    int i = 0;
    for(String englishWord: englishWords) {
        biMap.put(englishWord, russianWords[i]);
        i++;
    }

    // Print count words
    System.out.println(biMap); // print {two=dwa, ball=kula, one=jeden, snow=snieg, three=trzy} - in random orders
    // Print all unique words
    System.out.println(biMap.keySet());    // print [snow, two, one, three, ball] - in random orders
    System.out.println(biMap.values());    // print [dwa, kula, jeden, snieg, trzy] - in random orders

    // Print translate by words
    System.out.println("one = " + biMap.get("one"));    // print one = jeden
    System.out.println("two = " + biMap.get("two"));    // print two = dwa
    System.out.println("kula = " + biMap.inverse().get("kula"));    // print kula = ball
    System.out.println("snieg = " + biMap.inverse().get("snieg"));    // print snieg = snow
    System.out.println("empty = " + biMap.get("empty"));    // print empty = null

    // Print count word's pair
    System.out.println(biMap.size());    //print 5

3. HashMultiMap uit Guava

    String INPUT_TEXT = "Hello World! Hello All! Hi World!";
    // Parse text to words and index
    List<String> words = Arrays.asList(INPUT_TEXT.split(" "));
    // Create Multimap
    Multimap<String, Integer> multiMap = HashMultimap.create();
   
    // Fill Multimap
    int i = 0;
    for(String word: words) {
        multiMap.put(word, i);
        i++;
    }
   
    // Print all words
    System.out.println(multiMap); // print {Hi=[4], Hello=[0, 2], World!=[1, 5], All!=[3]} - keys and values in random orders
    // Print all unique words
    System.out.println(multiMap.keySet());    // print [Hi, Hello, World!, All!] - in random orders
   
    // Print all indexes
    System.out.println("Hello = " + multiMap.get("Hello"));    // print [0, 2]
    System.out.println("World = " + multiMap.get("World!"));    // print [1, 5]
    System.out.println("All = " + multiMap.get("All!"));    // print [3]
    System.out.println("Hi = " + multiMap.get("Hi"));    // print [4]
    System.out.println("Empty = " + multiMap.get("Empty"));    // print []
   
    // Print count all words
    System.out.println(multiMap.size());    //print 6
   
    // Print count unique words
    System.out.println(multiMap.keySet().size());    //print 4
   

Geen voorbeelden:

I. Apache-verzameling:

1. MultiValueMap
2. MultiValueMapLinked
3. MultiValueMapTree

II. GS / Eclipse-collectie

1. FastListMultimap
2. HashBagMultimap
3. TreeSortedSetMultimap
4. UnifiedSetMultimap

III. guava

1. HashMultiMap
2. LinkedHashMultimap
3. LinkedListMultimap
4. TreeMultimap
5. ArrayListMultimap

Operatie vergelijken met collecties - Collecties maken

Operatie vergelijken met collecties - Collecties maken

Voorbeelden:

    System.out.println("createArrayList start");
    // Create empty list
    List<String> emptyGuava = Lists.newArrayList(); // using guava
    List<String> emptyJDK = new ArrayList<>(); // using JDK
    MutableList<String>  emptyGS = FastList.newList(); // using gs

    // Create list with 100 element
    List < String > exactly100 = Lists.newArrayListWithCapacity(100); // using guava
    List<String> exactly100JDK = new ArrayList<>(100); // using JDK
    MutableList<String>  empty100GS = FastList.newList(100); // using gs

    // Create list with about 100 element
    List<String> approx100 = Lists.newArrayListWithExpectedSize(100); // using guava
    List<String> approx100JDK = new ArrayList<>(115); // using JDK
    MutableList<String>  approx100GS = FastList.newList(115); // using gs

    // Create list with some elements
    List<String> withElements = Lists.newArrayList("alpha", "beta", "gamma"); // using guava
    List<String> withElementsJDK = Arrays.asList("alpha", "beta", "gamma"); // using JDK
    MutableList<String>  withElementsGS = FastList.newListWith("alpha", "beta", "gamma"); // using gs

    System.out.println(withElements);
    System.out.println(withElementsJDK);
    System.out.println(withElementsGS);

    // Create list from any Iterable interface (any collection)
    Collection<String> collection = new HashSet<>(3);
    collection.add("1");
    collection.add("2");
    collection.add("3");

    List<String> fromIterable = Lists.newArrayList(collection); // using guava
    List<String> fromIterableJDK = new ArrayList<>(collection); // using JDK
    MutableList<String>  fromIterableGS = FastList.newList(collection); // using gs

    System.out.println(fromIterable);
    System.out.println(fromIterableJDK);
    System.out.println(fromIterableGS);
    /* Attention: JDK create list only from Collection, but guava and gs can create list from Iterable and Collection */

    // Create list from any Iterator
    Iterator<String> iterator = collection.iterator();
    List<String> fromIterator = Lists.newArrayList(iterator); // using guava
    System.out.println(fromIterator);

    // Create list from any array
    String[] array = {"4", "5", "6"};
    List<String> fromArray = Lists.newArrayList(array); // using guava
    List<String> fromArrayJDK = Arrays.asList(array); // using JDK
    MutableList<String>  fromArrayGS = FastList.newListWith(array); // using gs
    System.out.println(fromArray);
    System.out.println(fromArrayJDK);
    System.out.println(fromArrayGS);

    // Create list using fabric
    MutableList<String>  fromFabricGS = FastList.newWithNValues(10, () -> String.valueOf(Math.random())); // using gs
    System.out.println(fromFabricGS);

    System.out.println("createArrayList end");

Voorbeelden:

    System.out.println("createHashSet start");
    // Create empty set
    Set<String> emptyGuava = Sets.newHashSet(); // using guava
    Set<String> emptyJDK = new HashSet<>(); // using JDK
    Set<String> emptyGS = UnifiedSet.newSet(); // using gs

    // Create set with 100 element
    Set<String> approx100 = Sets.newHashSetWithExpectedSize(100); // using guava
    Set<String> approx100JDK = new HashSet<>(130); // using JDK
    Set<String> approx100GS = UnifiedSet.newSet(130); // using gs

    // Create set from some elements
    Set<String> withElements =  Sets.newHashSet("alpha", "beta", "gamma"); // using guava
    Set<String> withElementsJDK = new HashSet<>(Arrays.asList("alpha", "beta", "gamma")); // using JDK
    Set<String> withElementsGS  = UnifiedSet.newSetWith("alpha", "beta", "gamma"); // using gs

    System.out.println(withElements);
    System.out.println(withElementsJDK);
    System.out.println(withElementsGS);

    // Create set from any Iterable interface (any collection)
    Collection<String> collection = new ArrayList<>(3);
    collection.add("1");
    collection.add("2");
    collection.add("3");

    Set<String> fromIterable = Sets.newHashSet(collection); // using guava
    Set<String> fromIterableJDK = new HashSet<>(collection); // using JDK
    Set<String> fromIterableGS  = UnifiedSet.newSet(collection); // using gs

    System.out.println(fromIterable);
    System.out.println(fromIterableJDK);
    System.out.println(fromIterableGS);
    /* Attention: JDK create set only from Collection, but guava and gs can create set from Iterable and Collection */

    // Create set from any Iterator
    Iterator<String> iterator = collection.iterator();
    Set<String> fromIterator = Sets.newHashSet(iterator); // using guava
    System.out.println(fromIterator);

    // Create set from any array
    String[] array = {"4", "5", "6"};
    Set<String> fromArray = Sets.newHashSet(array); // using guava
    Set<String> fromArrayJDK = new HashSet<>(Arrays.asList(array)); // using JDK
    Set<String> fromArrayGS  = UnifiedSet.newSetWith(array); // using gs
    System.out.println(fromArray);
    System.out.println(fromArrayJDK);
    System.out.println(fromArrayGS);

    System.out.println("createHashSet end");

Voorbeelden:

    System.out.println("createHashMap start");
    // Create empty map
    Map<String, String> emptyGuava = Maps.newHashMap(); // using guava
    Map<String, String> emptyJDK = new HashMap<>(); // using JDK
    Map<String, String> emptyGS = UnifiedMap.newMap(); // using gs

    // Create map with about 100 element
    Map<String, String> approx100 = Maps.newHashMapWithExpectedSize(100); // using guava
    Map<String, String> approx100JDK = new HashMap<>(130); // using JDK
    Map<String, String> approx100GS = UnifiedMap.newMap(130); // using gs

    // Create map from another map
    Map<String, String> map = new HashMap<>(3);
    map.put("k1","v1");
    map.put("k2","v2");
    Map<String, String> withMap =  Maps.newHashMap(map); // using guava
    Map<String, String> withMapJDK = new HashMap<>(map); // using JDK
    Map<String, String> withMapGS = UnifiedMap.newMap(map); // using gs

    System.out.println(withMap);
    System.out.println(withMapJDK);
    System.out.println(withMapGS);

    // Create map from keys
    Map<String, String> withKeys =  UnifiedMap.newWithKeysValues("1", "a", "2", "b");
    System.out.println(withKeys);

    System.out.println("createHashMap end");

Meer voorbeelden: CreateCollectionTest

1. CollectionCompare
2. CollectionSearch
3. JavaTransform