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Last Updated: Jul 3, 2023
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HashMap entrySet() Method in Java

Author Akriti Bhan
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Introduction🎯

Java is emerging as a prevalent programming language these days. Java offers various advantages over other programming languages. There are multiple essential concepts in java that form its base. One such concept is entrySet java.

This blog will attempt to understand the hashmap entrySet java method. We will not start directly with entrySet java. This blog will first give you an overview of Java as a programming language and its applications followed by a discussion of hashmaps. Then we will finally move to the discussion of entrySet java.

about blog

Let us dive deep into the topic now.🎯

Java💻

Before discussing entrySet java, let us first discuss java as a programming language. Java was first introduced in 1995. Oracle owns JavaThe java syntax is straightforward to understand initially but becomes complex as the concept advances. Java is based on classes and is object-oriented in nature. It is a high-level language. Let us now look at the advantages of java✍

Also read, Duck Number in Java and  Hashcode Method in Java

Advantages of Java✅

advantages of java

Java is used to build and design mobile applications.

⭕It is used to build games.

⭕It is used in databases.

⭕Java is used to build desktop applications.

⭕Java plays a major role in the implementation of big data.

Also see,  Swap Function in Java

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Hashmap⭕

hashmaps

Our primary focus in this blog is to discuss the hashmap entrySet java. For this, one should have prior knowledge of hashmaps. Let us first explore hashmaps!😎

HashMap Class in Java📌

HashMap class in java is a very popular class due to the advantages that it provides. It provides the hash table data structure. The main property of hashmaps is that they store the data in the form of key-value pairs. This helps in the easy retrieval of the data.

Operations On Hashmaps📍

Hashmaps are of immense importance in writing some programs. Let us see some of the operations that we can perform on hashmaps are as follows.

⭕Accessing the elements

⭕Adding the elements

⭕Altering the elements

⭕Deleting the elements

Example🎯

Let us now create a hashmap in java for a better understanding of the concept.

import java.util.HashMap;
class hashmap {
    public static void main(String[] args) {

        HashMap<String, Integer> cars = new HashMap<>(); // declaring a hashmap

        cars.put("Maruti", 5); // putting elements into the hashmap
        cars.put("Honda", 100);
        System.out.println("HashMap created is : " + cars);
    }
}

Output

output

In the given example, we have created a hashmap named cars. We have stored the data in key-value pairs.

The pictorial representation of a hashmap for this example is shown.

pictorial

You can also check out Internal Working of HashMap

entrySet Java⭕

Now, that we are familiar with java as a programming language and the basic concepts of hashmaps, let us proceed to the HashMap entrySet java.

entryset java

entrySet java works on the concept of hashmaps. Its task is to return the data in the map in the hashmap simply. This data produced is in the form of a set. Another way of doing this is to create a new set. This set will now contain the mappings of data in the hashmap.

The syntax of the entrySet java is as follows📃

hashmap_obj.entrySet()

Here assume that we have created a class of Hashmap and hashmap_obj is an object of that class.

📌One important thing that we can infer from the syntax is that the brackets are empty. This means that entrySet java takes no parameters.

📌It is precisely written as java.util.HashMap.entrySet().

📌If we want to iterate through each data entry of the hashmap. We can use entrySet() with the for-each loop. The example to illustrate this is as follows.

Example

import java.util.HashMap;
import java.util.Map.Entry;

class hashmapp {
    public static void main(String[] args) {
        HashMap<String, Integer> cars = new HashMap<>(); // creating hashmap
        cars.put("Maruti", 100); // putting values into hashmap
        cars.put("Honda", 200);
        cars.put("BMW", 300);
        System.out.print("Entries of the hashmap are: ");

        for (Entry<String, Integer> data : cars.entrySet()) {
            System.out.print(data);
            System.out.print(", "); // printing data entries
        } }}

Output

output2

We hope you have understood the concept of HashMap entrySet() method in Java.🎯

Practice by yourself on online java compiler for better understanding.

Check out this article - Upcasting and Downcasting in Java

Frequently Asked Questions

What is the keySet() method in java?

As the name suggests, java's keySet() method returns all the keys in the mapping. These keys are in the form of a set.

Are duplicate keys allowed in the hashmap?

No, a hashmap cannot have duplicate keys. However, if you attempt to re-declare a key, its value will change, and the new value will dominate.

How many types of access specifiers are there in java?

There are primarily four types of access specifiers in java. These are public, private, protected, and default.

What is the main method in java?

The main method in java is the statement from where the java program starts executing. It is the entry point of the program.

How is data stored in the hashmap?

Hashmap stores the data in the form of key-value pairs forming a linked list internally. The data is stored in the nodes of this linked list in the form of a map.

You can also read about the topic -  hash function in data structure

Conclusion

In this blog, we discussed the entrySet() method in java in detail. We started with a discussion of java and its advantages. The blog further explored the hashmaps in detail. We also coded out an example of a hashmap for a better understanding. We then saw some important points about entrySet java and an example to better understand the concept.

You can refer to other similar articles as well


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Happy Learning Ninja! 🥷

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