As a Java programmer, you might have heard about the ConcurrentHashMap class of java.util.concurrent package. If you don’t let me tell you that ConcurrentHashMap is an important class in Java and you will often find yourself dealing with this class in a multithreaded and concurrent Java application. If you are wondering where to start and how to master this essential Java class then you have come to the right place.

In this article, I have shared some of the frequently used examples of ConcurrentHashMap in Java-like how to create a ConcurrentHashMap, how to update a key or value, how to delete a key-value pair, how to check if a key exists in ConcurrentHashMap or not, how to add new key-value pairs, and how to retrieve values from ConcurrentHashMap in Java.

Once you have gone through these examples, you will have a better understanding of ConcurrentHashMap and you will be more confident in using them in your Java program without causing subtle bugs that are hard to find and fix.

10 Examples of ConcurrentHashMap in Java

Without wasting any more of your time, here are 10 useful examples of ConcurrentHashMap in Java. By these examples, you will learn how to work with ConcurrentHashMap in Java, like creating a map, inserting key-value pairs, updating a key-value pair, deleting a mapping, check if a key or value exists in the map, iterating over keys or values, and so on.

1. How to Create a ConcurrentHashMap With Default Capacity

The first thing first, let’s learn how to create a concurrent hashmap in Java. Here is an example of creating an empty ConcurrentHashMapw ith default capacity.


ConcurrentHashMap programmingLanguages = new ConcurrentHashMap();

System.out.println("Empty ConcurrentHashMap : " + programmingLanguages);

2. How to Add Objects Into ConcurrentHashMap

Once you have created a ConcurrentHashMap, it’s time to add some mapping. let’s store some keys and values into a ConcurrentHashMap in Java. If you look at the below code its no different than the HashMa examples of adding mapping which we have seen before, the only difference is that its thread-safe.


programmingLanguages.put("Java", Integer.valueOf(18));
programmingLanguages.put("Scala", Integer.valueOf(10));
programmingLanguages.put("C++", Integer.valueOf(31));
programmingLanguages.put("C", Integer.valueOf(41));
System.out .println("ConcurrentHashMap with four mappings : " + programmingLanguages);

#java #tutorial #data structures #concurrenthashmap

10 Examples of ConcurrentHashMap in Java
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