Java ConcurrentHashMap get() Method

The get() method of ConcurrentHashMap class returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

Syntax

Parameter

key - the key whose associated value is to be returned

Returns

the value to which the specified key is mapped, or null if this map contains no mapping for the key

Throws

NullPointerException.

Example 1

import java.util.*; 
import java.util.concurrent.ConcurrentHashMap;
  
public class ConcurrentHashMapgetExample1 { 
    public static void main(String[] args) 
    { 
        ConcurrentHashMap<Integer, String> maphash = new ConcurrentHashMap<Integer, String>(); 
        maphash.put(1, "AA"); 
        maphash.put(2, "BB"); 
        maphash.put(3, "CC"); 
        maphash.put(4, "DD"); 
        maphash.put(5, "EE"); 
  
        System.out.println("mappings are: " + maphash); 
  
        System.out.println(" Value : " + maphash.get(6)); 
  
        System.out.println(" Value : " + maphash.get(4)); 
    } 
} 

Test it Now

Output:

mappings are: {1=AA, 2=BB, 3=CC, 4=DD, 5=EE}
 Value : null
 Value : DD

Example 2

import java.util.*; 
import java.util.concurrent.ConcurrentHashMap;
  
public class ConcurrentHashMapgetExample2 { 
    public static void main(String[] args) 
    { 
  
        ConcurrentHashMap<String , String> maphash = new ConcurrentHashMap<String , String>(); 
        
        maphash.put("A1", "AA"); 
        maphash.put("A2", "BB"); 
        maphash.put("A3", "CC"); 
        maphash.put("A4", "DD"); 
        maphash.put("A5", "EE"); 
  
        System.out.println("mappings are: " + maphash); 
  
        System.out.println(" Value : " + maphash.get("A1")); 
  
        System.out.println(" Value : " + maphash.get("A5")); 
    } 
} 

Test it Now

Output:

mappings are: {A1=AA, A2=BB, A3=CC, A4=DD, A5=EE}
 Value : AA
 Value : EE

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