Java ConcurrentHashMap merge() Method

by Online Tutorials Library July 22, 2022

Java ConcurrentHashMap merge() Method

The merge() method of ConcurrentHashMap class merge sets If the specified key is not already associated with a (non-null) value, associates it with the given value.

Syntax

  public V merge(K key, V value, BiFunction<? super V,? super V,? extends V> remappingFunction)  

Parameter

key – key with which the specified value is to be associated

value – the value to use if absent

remappingFunction – the function to recompute a value if present

Returns

The new value associated with the specified key, or null if none

Throws

No Exception is thrown.

Example 1

  import java.util.*;   import java.util.concurrent.*;       public class ConcurrentHashMapmergeExample1  {       public static void main(String[] args)       {           ConcurrentHashMap  conmap = new ConcurrentHashMap();                     conmap.put(1, “Java”);                  conmap.put(2, “php”);                  conmap.put(3, “.net”);                  conmap.put(5, “python”);                    ConcurrentHashMap  conmap2 = new ConcurrentHashMap();                     conmap2.put(1, “C”);                  conmap2.put(2, “C++”);                  conmap2.put(3, “Rubi”);                  conmap2.put(5, “Java Script”);                                    conmap2.forEach(                        (key, value) -> conmap.merge( key, value, (v1, v2) -> v1.equalsIgnoreCase(v2) ? v1 : v1 + “,” + v2)                                 );                           System.out.println(conmap);         }   }  ,>,>,>,>

Test it Now

Output:

{1=Java,C, 2=php,C++, 3=.net,Rubi, 5=python,Java Script}

Example 2

  import java.util.*;   import java.util.concurrent.*;       public class ConcurrentHashMapmergeExample2  {       public static void main(String[] args)       {           ConcurrentHashMap  conmap = new ConcurrentHashMap();                     conmap.put(1, “A”);                  conmap.put(2, “B”);                  conmap.put(3, “C”);                  conmap.put(5, “E”);                    ConcurrentHashMap  conmap2 = new ConcurrentHashMap();                     conmap2.put(1, “F”);                  conmap2.put(2, “G”);                  conmap2.put(3, “H”);                  conmap2.put(5, “I”);                                    conmap2.forEach(                        (key, value) -> conmap.merge( key, value, (v1, v2) -> v1.equalsIgnoreCase(v2) ? v1 : v1 + “,” + v2)                                 );     System.out.println(conmap);                }   }  ,>,>,>,>

Test it Now

Output:

{1=A,F, 2=B,G, 3=C,H, 5=E,I}

Next TopicJava ConcurrentHashMap

Java ConcurrentHashMap merge() Method

Java ConcurrentHashMap merge() Method

Syntax

Parameter

Returns

Throws

Example 1

Example 2

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