Java LinkedHashMap get() Method

The LinkedHashMap.get() method in Java is used to retrieve the value associated with a specific key in a LinkedHashMap.

Table of Contents

1. Introduction
2. get Method Syntax
3. Examples
   • Retrieving Values from a LinkedHashMap
   • Handling Non-Existent Keys
4. Real-World Use Case
   • Example: Retrieving User Profile Information
5. Conclusion

Introduction

The LinkedHashMap.get() method is a member of the LinkedHashMap class in Java. It allows you to retrieve the value associated with a specific key. If the key is not found, the method returns null. This can be useful in scenarios where you need to access values based on their keys.

get() Method Syntax

The syntax for the get method is as follows:

public V get(Object key)

• The method takes one parameter:
  • key of type Object, which represents the key whose associated value is to be returned.
• The method returns the value associated with the specified key, or null if the map contains no mapping for the key.

Examples

Retrieving Values from a LinkedHashMap

The get method can be used to retrieve values based on their keys from a LinkedHashMap.

Example

import java.util.LinkedHashMap;

public class GetExample {
    public static void main(String[] args) {
        // Creating a LinkedHashMap with String keys and Integer values
        LinkedHashMap<String, Integer> people = new LinkedHashMap<>();

        // Adding entries to the LinkedHashMap
        people.put("Ravi", 25);
        people.put("Priya", 30);
        people.put("Vijay", 35);

        // Retrieving values from the LinkedHashMap
        Integer ageRavi = people.get("Ravi");
        Integer agePriya = people.get("Priya");
        Integer ageVijay = people.get("Vijay");

        // Printing the retrieved values
        System.out.println("Age of Ravi: " + ageRavi);
        System.out.println("Age of Priya: " + agePriya);
        System.out.println("Age of Vijay: " + ageVijay);
    }
}

Output:

Age of Ravi: 25
Age of Priya: 30
Age of Vijay: 35

Handling Non-Existent Keys

The get method returns null if the specified key is not found in the LinkedHashMap.

Example

import java.util.LinkedHashMap;

public class NonExistentKeyExample {
    public static void main(String[] args) {
        // Creating a LinkedHashMap with String keys and Integer values
        LinkedHashMap<String, Integer> people = new LinkedHashMap<>();

        // Adding entries to the LinkedHashMap
        people.put("Ravi", 25);
        people.put("Priya", 30);
        people.put("Vijay", 35);

        // Attempting to retrieve a value for a non-existent key
        Integer ageAmit = people.get("Amit");

        // Checking if the key exists and printing the result
        if (ageAmit == null) {
            System.out.println("Key 'Amit' does not exist in the LinkedHashMap.");
        } else {
            System.out.println("Age of Amit: " + ageAmit);
        }
    }
}

Output:

Key 'Amit' does not exist in the LinkedHashMap.

Real-World Use Case

Example: Retrieving User Profile Information

A common real-world use case for LinkedHashMap.get() is retrieving user profile information based on a username. For example, let's consider a scenario where user profiles are stored in a LinkedHashMap, and we need to retrieve the profile information for a given username.

Example

import java.util.LinkedHashMap;

public class UserProfile {
    public static void main(String[] args) {
        // Creating a LinkedHashMap to store user profiles
        LinkedHashMap<String, String> userProfiles = new LinkedHashMap<>();

        // Adding user profiles to the LinkedHashMap
        userProfiles.put("Ravi", "Profile information for Ravi.");
        userProfiles.put("Priya", "Profile information for Priya.");
        userProfiles.put("Vijay", "Profile information for Vijay.");

        // Retrieving user profile information
        String raviProfile = userProfiles.get("Ravi");
        String priyaProfile = userProfiles.get("Priya");
        String amitProfile = userProfiles.get("Amit"); // Non-existent key

        // Printing the user profile information
        System.out.println("Ravi's Profile: " + raviProfile);
        System.out.println("Priya's Profile: " + priyaProfile);

        if (amitProfile == null) {
            System.out.println("Profile for Amit does not exist.");
        } else {
            System.out.println("Amit's Profile: " + amitProfile);
        }
    }
}

Output:

Ravi's Profile: Profile information for Ravi.
Priya's Profile: Profile information for Priya.
Profile for Amit does not exist.

In this example, LinkedHashMap.get() is used to retrieve user profile information based on the username, demonstrating how to handle both existing and non-existent keys.

Conclusion

The LinkedHashMap.get() method in Java provides a way to retrieve the value associated with a specific key in a LinkedHashMap. By understanding how to use this method, you can efficiently access values based on their keys in your Java applications. The method allows you to handle both existing and non-existent keys, making it a versatile tool for data management.