JAVA

hashmap in java

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class HashhMap {
    public static void main(String[] args){
        Map<String, String> map = new HashMap<>();
        map.put("myName","Kumaran");
        map.put("myProgram", "Java");
        map.put("Designation", "Java Developer");

        Set<String> key = map.keySet();


        for(String keys: key){
            System.out.println(keys+ " : "  +map.get(keys));
        }
    }
}

HashMap java

package org.o7planning.tutorial.javacollection.helloworld;

import java.util.HashMap;

public class HelloHashMap {

	public static void main(String[] args) {

		// Créer un objet HashMap qui stocke les paires des ID d'employés et des salaires.
		// Clé de chaîne: ID d'employé
		// Valeur flottante: Salaire.
		HashMap<String, Float> salaryMap = new HashMap<String, Float>();
	 

		salaryMap.put("E01", 1000f);
		salaryMap.put("E02", 12000f);
		salaryMap.put("E03", 12300f);
		salaryMap.put("E04", 1000f);
		salaryMap.put("E05", 300.5f);
		
		// Obtenir les salaires des employés 'E02'
		Float salary= salaryMap.get("E01");
		System.out.println("Salary of employee E01 = "+ salary);
		
		// Mettre à jour le salaire pour les employés 'E05'
		salaryMap.put("E05", 400f);
		
		System.out.println("Salary of employee E05 = "+ salaryMap.get("E05"));
		 
	}

}

Hashmap

#include <iostream>
#include <string>
#include <unordered_map>
 
int main()
{
    // Create an unordered_map of three strings (that map to strings)
    std::unordered_map<std::string, std::string> u = {
        {"RED","#FF0000"},
        {"GREEN","#00FF00"},
        {"BLUE","#0000FF"}
    };
 
    // Helper lambda function to print key-value pairs
    auto print_key_value = [](const auto& key, const auto& value) {
        std::cout << "Key:[" << key << "] Value:[" << value << "]
";
    };
 
    std::cout << "Iterate and print key-value pairs of unordered_map, being
"
                 "explicit with their types:
";
    for( const std::pair<const std::string, std::string>& n : u ) {
        print_key_value(n.first, n.second);
    }
 
    std::cout << "
Iterate and print key-value pairs using C++17 structured binding:
";
    for( const auto& [key, value] : u ) {
        print_key_value(key, value);
    }
 
    // Add two new entries to the unordered_map
    u["BLACK"] = "#000000";
    u["WHITE"] = "#FFFFFF";
 
    std::cout << "
Output values by key:
"
                 "The HEX of color RED is:[" << u["RED"] << "]
"
                 "The HEX of color BLACK is:[" << u["BLACK"] << "]

";
 
    std::cout << "Use operator[] with non-existent key to insert a new key-value pair:
";
    print_key_value("new_key", u["new_key"]);
 
    std::cout << "
Iterate and print key-value pairs, using `auto`;
"
                 "new_key is now one of the keys in the map:
";
    for( const auto& n : u ) {
        print_key_value(n.first, n.second);
    }
}

hashmap java

    private static final Map<Integer, String> map = Map.of(
        1, "one",
        2, "two"
    );

Java HashMap

import java.util.HashMap; // import the HashMap class

HashMap<String, String> capitalCities = new HashMap<String, String>();

hashmap

- HasHMap can have null key, order is not guaranteed

Hashmap

// hashMap creation with 8 capacity and 0.6 load factor
HashMap<K, V> numbers = new HashMap<>();

HashMap<String, Integer> numbers = new HashMap<>();