Java HashMap get() Method

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

Table of Contents

1. Introduction
2. get Method Syntax
3. Examples
   • Retrieving Values from a HashMap
   • Real-World Use Case: Retrieving Employee Names
4. Conclusion

Introduction

The HashMap.get() method is a member of the HashMap class in Java. It allows you to retrieve the value associated with a specific key. This can be useful when you need to access data stored in a HashMap based on a key.

get() Method Syntax

The syntax for the get method is as follows:

public V get(Object key)

• The method takes a single 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 HashMap

The get method can be used to retrieve the value associated with a specific key from a HashMap.

Example

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

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

        // Adding entries to the HashMap
        countries.put("India", "IN");
        countries.put("United States", "US");
        countries.put("Canada", "CA");

        // Retrieving values from the HashMap
        String indiaCode = countries.get("India");
        String brazilCode = countries.get("Brazil"); // This will return null

        // Printing the results
        System.out.println("Country code for India: " + indiaCode);
        System.out.println("Country code for Brazil: " + brazilCode);
    }
}

Output:

Country code for India: IN
Country code for Brazil: null

Real-World Use Case: Retrieving Employee Names

In a real-world scenario, you might use the get method to retrieve employee names from a company’s employee database using employee IDs.

Example

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

public class EmployeeNameRetrieval {
    public static void main(String[] args) {
        // Creating a Map with String keys (employee IDs) and String values (employee names)
        Map<String, String> employeeDatabase = new HashMap<>();

        // Adding entries to the HashMap
        employeeDatabase.put("E001", "Ravi Kumar");
        employeeDatabase.put("E002", "Priya Sharma");
        employeeDatabase.put("E003", "Vijay Singh");

        // Employee ID to be searched
        String employeeIdToSearch = "E002";

        // Retrieving the employee name using the employee ID
        String employeeName = employeeDatabase.get(employeeIdToSearch);

        // Printing the employee name
        if (employeeName != null) {
            System.out.println("Employee ID " + employeeIdToSearch + " is associated with employee name: " + employeeName);
        } else {
            System.out.println("Employee ID " + employeeIdToSearch + " does not exist in the database.");
        }
    }
}

Output:

Employee ID E002 is associated with employee name: Priya Sharma

Conclusion

The HashMap.get() method in Java provides a way to retrieve the value associated with a specific key from a HashMap. By understanding how to use this method, you can efficiently access data stored in a HashMap based on keys. This method is useful in various scenarios, such as retrieving records from a database, accessing configuration settings, and managing collections of data.