CODE EXAMPLE FOR JAVA

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);
    }
}