MultiValueMap. multiValueMap( new TreeMap<K, Set>(),TreeSet.class)
TreeMap<K, TreeSet<V>>
Task: Parse "Hello World! Hello All! Hi World!" string to separate words and print all indexes of every word using MultiMap (for example, Hello=[0, 2], World!=[1, 5] and so on)
1. MultiValueMap from 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 from GS / Eclipse Collection
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
HashMultiMap from Guava
String INPUT_TEXT ="Hello World! Hello All! Hi World!";// Parse text to words and indexList<String> words =Arrays.asList(INPUT_TEXT.split(" "));// Create MultimapMultimap<String,Integer> multiMap =HashMultimap.create();// Fill Multimapint i =0;for(String word: words){
multiMap.put(word, i);
i++;}// Print all wordsSystem.out.println(multiMap);// print {Hi=[4], Hello=[0, 2], World!=[1, 5], All!=[3]} - keys and values in random orders// Print all unique wordsSystem.out.println(multiMap.keySet());// print [Hi, Hello, World!, All!] - in random orders// Print all indexesSystem.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 wordsSystem.out.println(multiMap.size());//print 6// Print count unique wordsSystem.out.println(multiMap.keySet().size());//print 4
Apache HashBag, Guava HashMultiset and Eclipse HashBag
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.
Compare operation with collections - Create collections
Compare operation with collections - Create collections
Description
JDK
guava
gs-collections
Create empty list
new ArrayList<>()
Lists.newArrayList()
FastList.newList()
Create list from values
Arrays.asList("1", "2", "3")
Lists.newArrayList("1", "2", "3")
FastList.newListWith("1", "2", "3")
Create list with capacity = 100
new ArrayList<>(100)
Lists.newArrayListWithCapacity(100)
FastList.newList(100)
Create list from any collectin
new ArrayList<>(collection)
Lists.newArrayList(collection)
FastList.newList(collection)
Create list from any Iterable
-
Lists.newArrayList(iterable)
FastList.newList(iterable)
Create list from Iterator
-
Lists.newArrayList(iterator)
-
Create list from array
Arrays.asList(array)
Lists.newArrayList(array)
FastList.newListWith(array)
Create list using factory
-
-
FastList.newWithNValues(10, () -> "1")
Examples:
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");
Description
JDK
guava
gs-collections
Create empty set
new HashSet<>()
Sets.newHashSet()
UnifiedSet.newSet()
Creatre set from values
new HashSet<>(Arrays.asList("alpha", "beta", "gamma"))
Sets.newHashSet("alpha", "beta", "gamma")
UnifiedSet.newSetWith("alpha", "beta", "gamma")
Create set from any collections
new HashSet<>(collection)
Sets.newHashSet(collection)
UnifiedSet.newSet(collection)
Create set from any Iterable
-
Sets.newHashSet(iterable)
UnifiedSet.newSet(iterable)
Create set from any Iterator
-
Sets.newHashSet(iterator)
-
Create set from Array
new HashSet<>(Arrays.asList(array))
Sets.newHashSet(array)
UnifiedSet.newSetWith(array)
Examples:
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");
Description
JDK
guava
gs-collections
Create empty map
new HashMap<>()
Maps.newHashMap()
UnifiedMap.newMap()
Create map with capacity = 130
new HashMap<>(130)
Maps.newHashMapWithExpectedSize(100)
UnifiedMap.newMap(130)
Create map from other map
new HashMap<>(map)
Maps.newHashMap(map)
UnifiedMap.newMap(map)
Create map from keys
-
-
UnifiedMap.newWithKeysValues("1", "a", "2", "b")
Examples:
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");