HashMap implementation of java

             Map is an interface which stores key and value. It has various types of implementations. One of those implementations is “HashMap”.

HashMap implementation includes the following built-in functions listed below.

put(): adding key, value to the HashMap.

get(): This function gets the key and value.

containsKey(): This function checks a value is available or not.

getKey(): It gets the key.

getValue() :It retrieves the value associated with the key.

remove() :This function deletes the entry.

size() :This gives you the size of the HashMap.

clear() :It clear all the keys and values.

isEmpty(): This returns Boolean value to check the HashMap is empty or not.

Program:

import java.util.HashMap;

import java.util.Map;

public class HashMapEg {

    public static void main(String[] args) {

        // Let us create a HashMap

        Map<String, String> map1 = new HashMap<>();

        //Insert the values to the HashMap as key and value.

        map1.put("Car", "Vehicle");

        map1.put("Cricket", "Sports");

        map1.put("Shirt", "Dress");

        map1.put("Juice","Drink");

        map1.put("Orange","Fruit");

        // retrieve a value by searching by key value

        System.out.println("Car is a " + map1.get("Car"));

        // checking for an entry

        if (map1.containsKey("Cricket")) {

            System.out.println("Cricket is present in the map.");

        }

        // Loop to print the keys and values in the HashMap

        for (Map.Entry<String, String> entry : map1.entrySet()) {

            System.out.println(entry.getKey() + " is a " + entry.getValue());

        }

        // delete a key and value

        map1.remove("Fruit");

       // print the size of hashmap

        System.out.println("Size of the map: " + map1.size());

        // Clearing all the key,value pair

        map1.clear();

        //Check for map is empty or not

        if(map1.isEmpty())

        System.out.println("The map is empty" + map1.isEmpty());

    }

}

Output:

C:\raji\blog>javac HashMapEg.java

C:\raji\blog>java HashMapEg

Car is a Vehicle

Cricket is present in the map.

Cricket is a Sports

Shirt is a Dress

Car is a Vehicle

Juice is a Drink

Orange is a Fruit

Size of the map: 5

The map is empty

This is the simple implementation of HashMap using java programming. Hope this will be useful for you. Keep coding!!!