Java ConcurrentHashMap containsKey() Method

The containsKey() method of ConcurrentHashMap class tests if the specified object is a key in this table.

Syntax

Parameter

key - possible key

Returns

true if and only if the specified object is a key in this table, as determined by the equals method; false otherwise

Throws

NullPointerException

Example 1

import java.util.*; 
import java.util.concurrent.*; 
  
public class ConcurrentHashMapcontainsKeyExample1  { 
    public static void main(String[] args) 
    { 
        ConcurrentHashMap<String, Integer>  map = new ConcurrentHashMap<String,  Integer>(); 
  
        map.put("java", 10); 
        map.put(".net", 15); 
        map.put("python", 20); 
        map.put("c", 25); 
        map.put("c++", 30); 

        System.out.println(" Mappings are: " +map); 

        System.out.println("is java  present? ::  " + map.containsKey("java"));   //check if map contains key javascript
 
    } 
} 

Test it Now

Output:

Mappings are: {python=20, c++=30, java=10, c=25, .net=15}
is java  present? ::  true

Example 2

import java.util.*; 
import java.util.concurrent.*; 
  
public class ConcurrentHashMapcontainsKeyExample2  { 
    public static void main(String[] args) 
    { 
        ConcurrentHashMap<String, Integer>  map = new ConcurrentHashMap<String,  Integer>(); 
  
        map.put("java", 10); 
        map.put(".net", 15); 
        map.put("python", 20); 
        map.put("c", 25); 
        map.put("c++", 30); 

        System.out.println(" Mappings are: " +map);   //print the map

        System.out.println("is javascript  present? ::  "+ map.containsKey("javascript"));   //check if map contains key javascript
 
    } 
}

Test it Now

Output:

Mappings are: {python=20, c++=30, java=10, c=25, .net=15}
is javascript  present? ::  false

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