How To Piece Of Job Concurrenthashset From Concurrenthashmap Inwards Coffee Viii - Illustration Tutorial

There is no ConcurrentHashSet inward JDK 8 but yous tin laissez passer the sack nevertheless practice 1 for yourself past times using the ConcurrentHashMap shape of java.util.concurrent package. There is a novel method added into ConcurrentHashMap inward JDK 8, newKeySet(), which allows yous to practice a concurrent hash ready backed past times a concurrent hash map. If yous scream back whenever yous teach keys from the map they are returned inward a Set e.g. for the former keySet() method because map solely has unique keys. Since map doesn't permit duplicate keys, it tin laissez passer the sack last used equally a set, equally long equally yous solely help for keys or simply 1 element. That's why Java designers are added newKeySet() method to convert a map to set. This is too a static method, which agency yous don't postulate a ConcurrentHashMap object to practice a concurrent hash set.

The Set returned past times the keySet() method is backed past times a ConcurrentHashMap amongst given keys as well as values are ever Boolean.TRUE. It is too overloaded to conduct maintain initial capacity to avoid internal re-sizing. If yous know, the HashSet shape too internally uses an HashMap where values are ever same, an object, which is possible because Map allows duplicate values.

Unlike the List returned past times Arrays.asList(), which doesn't permit yous to add together or take elements, the Set returned past times newKeySet() is similar whatever normal Set implementations as well as allows yous add, take or perform whatever other Set operation. You tin laissez passer the sack fifty-fifty top this Set to a method which is accepting a Set interface equally a parameter. I'll demonstrate this inward coming example.

Java Program to practice ConcurrentHashSet

Here is our Java programme to demonstrate how yous tin laissez passer the sack generate a ConcurrentHashSet inward JDK 8 past times using the newKeSet() method added into java.util.concurrent.ConcurrentHashMap class. Even though I conduct maintain used an object of the concurrent hash map here, it's non required because dissimilar keySet(), the newKeySet() is a static method.

Let's the code to genuinely generate a concurrent hash ready inward Java 8:

import java.util.Set; import java.util.concurrent.ConcurrentHashMap;  /*  * Java Program to practice ConcurrentHashSet from ConcurrentHashMap  * This code requires JDK 8 because nosotros role newKeySet() method  * which is solely available inward ConcurrentHashMap shape from JDK 8.   */ public class Demo {    public static void main(String[] args) throws Exception {      // measuring 1 - practice a concurrent hashmap (optional)     ConcurrentHashMap<String, Integer> wordLengh = new ConcurrentHashMap<>();      // measuring two - practice a ready from map past times using newKeySet() method     // supply size to forestall resizing as well as amend performance     Set<String> words = ConcurrentHashMap.newKeySet(wordLengh.size());      // measuring iii - yous tin laissez passer the sack add together elements into set     words.add("Java");     words.add("JavaScript");      // measuring iv - yous tin laissez passer the sack take elements from set     words.remove("JavaScript");      // measuring five - yous tin laissez passer the sack too top this ready to whatever method expecting set     System.out.println(words);    }  }  Output: [Java]

You tin laissez passer the sack encounter that yous tin laissez passer the sack easily add together as well as take elements from the Set returned past times newKeySet() method. As I said, the Set is backed past times ConcurrentHashMap, which agency multiple readers tin laissez passer the sack retrieve values at the same fourth dimension as well as too multiple writers tin laissez passer the sack insert values into the ready without blocking, until the read as well as write functioning is happening inward the same segment. You tin laissez passer the sack too see answer)
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