Apache HashBag, Guava HashMultiset and Eclipse HashBag

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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 customInputText = "How are you? How is everything?";
 
// Create Multiset
Bag customBag = SynchronizedSortedBag.synchronizedBag(new TreeBag(Arrays.asList(customInputText.split(" "))));
 
// Print count words
System.out.println(customBag); // print [1:How, 1:How, 1:are, 1:everything?, 1:is, 1:you?]- in natural (alphabet) order
 
// Print all unique words
System.out.println(customBag.uniqueSet()); // print [How, are, everything?, is, you?]- in natural (alphabet) order
 
// Print count occurrences of words
System.out.println("How = " + customBag.getCount("How")); // print 2
System.out.println("are = " + customBag.getCount("are")); // print 1
System.out.println("you? = " + customBag.getCount("you?")); // print 1
System.out.println("is = " + customBag.getCount("is")); // print 1
System.out.println("everything? = " + customBag.getCount("everything?")); // print 1
System.out.println("Empty = " + customBag.getCount("Empty")); // print 0
 
// Print count all words
System.out.println(customBag.size()); //print 6
 
// Print count unique words
System.out.println(customBag.uniqueSet().size()); //print 5

2. Using TreeBag from Eclipse(GC):

// Parse text to separate words
String customInputText = "Greetings Universe! Hello Everyone! Hi Universe!";
 
// Create Multiset
MutableSortedBag<String> customBag = TreeBag.newBag(Arrays.asList(customInputText.split(" ")));
 
// Print count words
System.out.println(customBag); // print [Everyone!, Greetings, Hello, Hello, Hi, Universe!, Universe!]- in natural order
 
// Print all unique words
System.out.println(customBag.toSortedSet()); // print [Everyone!, Greetings, Hello, Hi, Universe!]- in natural order
 
// Print count occurrences of words
System.out.println("Hello = " + customBag.occurrencesOf("Hello")); // print 2
System.out.println("Universe = " + customBag.occurrencesOf("Universe!")); // print 2
System.out.println("Greetings = " + customBag.occurrencesOf("Greetings")); // print 1
System.out.println("Hi = " + customBag.occurrencesOf("Hi")); // print 1
System.out.println("Empty = " + customBag.occurrencesOf("Empty")); // print 0
 
// Print count all words
System.out.println(customBag.size()); // print 6
 
// Print count unique words
System.out.println(customBag.toSet().size()); // print 5

3. Using LinkedHashMultiset from Guava:

// Parse text to separate words
String customInputText = "How are you? How are all of you doing today?";
 
// Create Multiset
Multiset<String> customMultiset = LinkedHashMultiset.create(Arrays.asList(customInputText.split(" ")));
 
// Print count words
System.out.println(customMultiset); // print [How x 2, are x 2, you?, all x 2, of, doing, today?]- in predictable iteration order
 
// Print all unique words
System.out.println(customMultiset.elementSet()); // print [How, are, you?, all, of, doing, today?] - in predictable iteration order
 
// Print count occurrences of words
System.out.println("How = " + customMultiset.count("How")); // print 2
System.out.println("are = " + customMultiset.count("are")); // print 2
System.out.println("you? = " + customMultiset.count("you?")); // print 1
System.out.println("all = " + customMultiset.count("all")); // print 2
System.out.println("of = " + customMultiset.count("of")); // print 1
System.out.println("doing = " + customMultiset.count("doing")); // print 1
System.out.println("today? = " + customMultiset.count("today?")); // print 1
System.out.println("Empty = " + customMultiset.count("Empty")); // print 0
 
// Print count all words
System.out.println(customMultiset.size()); //print 10
 
// Print count unique words
System.out.println(customMultiset.elementSet().size()); //print 7

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