Java ConcurrentHashMap mappingCount() Method

by Online Tutorials Library July 22, 2022

Java ConcurrentHashMap mappingCount() Method

The mappingCount() method of ConcurrentHashMap class returns the number of mappings. The value returned is an estimated value; the actual count may differ if there are concurrent insertions or removals.

Syntax

Parameter

No parameter is passed.

Returns

the number of mappings

Throws

No exception is thrown.

Example 1

  import java.util.concurrent.ConcurrentHashMap;   import java.util.*;       public class ConcurrentHashMapmappingCountExample1 {           public static void main(String[] args)       {           ConcurrentHashMap chm = new ConcurrentHashMap();             chm.put(“1”, “1”);           chm.put(“2”, “10”);           chm.put(“3”, “100”);           chm.put(“4”, “2”);           chm.put(“5”, “20”);           chm.put(“6”, “200”);            // print statement.          System.out.println(“size of map before clearing: ” + chm.mappingCount());           chm.clear(); // clear will clear all the values in map.          System.out.println(“Map after calling clear(): “+ chm);           System.out.println(“size of map after clearing: ” + chm.mappingCount());       }   }  ,>,>

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Output:

size of map before clearing: 6  Map after calling clear(): {}  size of map after clearing: 0

Example 2

  import java.util.*;   import java.util.concurrent.*;       public class ConcurrentHashMapmappingCountExample2  {       public static void main(String[] args)       {           ConcurrentHashMap  conmap = new ConcurrentHashMap();           conmap.put(10, “Java”);           conmap.put(11, “.net”);           conmap.put(20, “php”);           conmap.put(12, “C”);           conmap.put(30, “C++”);               System.out.println(” Map : ” + conmap);                     System.out.println(“keySet : ” + conmap.keySet());           System.out.println(“Map Size  : ” + conmap.mappingCount());      }   }  ,>,>

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Output:

Map : {20=php, 10=Java, 11=.net, 12=C, 30=C++}  keySet : [20, 10, 11, 12, 30]  Map Size  : 5

Next TopicJava ConcurrentHashMap

Java ConcurrentHashMap mappingCount() Method

Java ConcurrentHashMap mappingCount() Method

Syntax

Parameter

Returns

Throws

Example 1

Example 2

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