Java Language Alternative Collections Apache HashBag, Guava HashMultiset and Eclipse HashBag
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Example
A Bag/ultiset stores each object in the collection together with a count of occurrences. Extra methods on the interface allow multiple copies of an object to be added or removed at once. JDK analog is HashMap<T, Integer>, when values is count of copies this key.
| Type | Guava | Apache Commons Collections | GS Collections | JDK |
|---|---|---|---|---|
| Order not defined | HashMultiset | HashBag | HashBag | HashMap |
| Sorted | TreeMultiset | TreeBag | TreeBag | TreeMap |
| Insertion-order | LinkedHashMultiset | - | - | LinkedHashMap |
| Concurrent variant | ConcurrentHashMultiset | SynchronizedBag | SynchronizedBag | Collections.synchronizedMap(HashMap<String, Integer>) |
| Concurrent and sorted | - | SynchronizedSortedBag | SynchronizedSortedBag | Collections.synchronizedSortedMap(TreeMap<String,Integer>) |
| Immutable collection | ImmutableMultiset | UnmodifiableBag | UnmodifiableBag | Collections.unmodifiableMap(HashMap<String, Integer)] |
| Immutable and sorted | ImmutableSortedMultiset | UnmodifiableSortedBag | UnmodifiableSortedBag | Collections.unmodifiableSortedMap(TreeMap<String, Integer>) |
Examples:
1. Using SynchronizedSortedBag from 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. Using TreeBag from Eclipse(GC):
// 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. Using LinkedHashMultiset from Guava:
// 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
More examples:
I. Apache Collection:
- HashBag - order not defined
- SynchronizedBag - concurrent and order not defined
- SynchronizedSortedBag - - concurrent and sorted order
- TreeBag - sorted order
II. GS / Eclipse Collection
- MutableBag - order not defined
- MutableSortedBag - sorted order
III. Guava
- HashMultiset - order not defined
- TreeMultiset - sorted order
- LinkedHashMultiset - insertion order
- ConcurrentHashMultiset - concurrent and order not defined
