My Journey with LinkedHashMap: From Chaos to Calm
The Dilemma
I remember the first time I was assigned a project that involved dealing with a massive dataset for a food delivery app. The project wasn’t just about handling data; it was about making sense of it.
Imagine being handed a basket full of unordered items—like a random assortment of Haldiram’s snacks, KFC buckets, Dominos pizzas, Momos, and Subway sandwiches—and being asked to organize them based on their order of arrival.
Sounds simple, right? But it wasn’t.
The dataset was messy, just like a chaotic food festival with stalls popping up randomly. The challenge was to not only keep track of the order but also efficiently retrieve the data when needed.
I started thinking about how I could solve this problem using Java. That’s when I stumbled upon LinkedHashMap.
Understanding LinkedHashMap
For those who aren’t familiar, LinkedHashMap in Java is like your reliable friend who remembers everything in the order you told them. It’s a part of the Java Collections Framework and extends HashMap, which means it stores key-value pairs.
But unlike HashMap, which doesn’t maintain any order, LinkedHashMap maintains the order of elements based on their insertion. It’s like keeping a mental note of the order in which you visited Haldiram’s, then KFC, and then Dominos.
LinkedHashMap<String, String> foodOrder = new LinkedHashMap<>();
foodOrder.put("Priya", "Subway");
foodOrder.put("Akash", "Momos");
foodOrder.put("Shubham", "KFC");I quickly realized that LinkedHashMap was my tool of choice. It allowed me to maintain the insertion order of elements, which was crucial for my task.
But as I delved deeper, I faced a new challenge: converting LinkedHashMap to a generic object in Java.
The Emotional Rollercoaster
Now, let me take you on a journey—a journey filled with highs, lows, and a few conflicts. The first hurdle was when Priya, my colleague, suggested using a different data structure.
She believed that a TreeMap, which sorts elements based on their natural ordering, would be more efficient. But I knew that maintaining the order of insertion was critical for this project.
We had a heated debate, akin to deciding whether to grab a burger from KFC or a pizza from Dominos when both options seemed equally tempting.
I stood my ground and opted for LinkedHashMap.
The insertion order was non-negotiable. But this decision led me to another problem—how do I convert this LinkedHashMap into a generic object?
The Struggle of Conversion
Converting a LinkedHashMap to a generic object isn’t as straightforward as ordering a meal at Subway.
It requires understanding the data structure and how Java’s type system works.
The first step was to create a generic class that could hold the data. But it wasn’t that simple.
I faced a new conflict with Akash, a fellow developer, who believed that creating a generic object was overcomplicating things. He argued that we could stick to a map and call it a day.
import java.lang.reflect.Field;
import java.util.LinkedHashMap;
public class LinkedHashMapToObject {
public static <T> T convertMapToObject(LinkedHashMap<String, Object> map, Class<T> clazz) throws Exception {
T instance = clazz.getDeclaredConstructor().newInstance();
for (Map.Entry<String, Object> entry : map.entrySet()) {
Field field = clazz.getDeclaredField(entry.getKey());
field.setAccessible(true);
field.set(instance, entry.getValue());
}
return instance;
}
}But I wasn’t satisfied. I wanted something more—something that would allow us to work with the data as if it were a fully-fledged object.
After hours of brainstorming and several cups of coffee (and maybe a few bags of Haldiram’s snacks), I finally came up with a solution.
Examples of Using LinkedHashMap
Tracking food orders was my first example. Imagine you’re handling orders from different customers—Priya orders a Subway sandwich, Akash orders Momos, and Shubham orders a KFC bucket.
You can store these orders in a LinkedHashMap to maintain the order of their placement. When you retrieve the orders, they’ll come out in the same sequence: Priya first, then Akash, then Shubham.
LinkedHashMap<String, String> foodOrder = new LinkedHashMap<>();
foodOrder.put("Priya", "Subway");
foodOrder.put("Akash", "Momos");
foodOrder.put("Shubham", "KFC");Another example involved customer details. Suppose you have customer details like name, order, and price for each order—Priya ordered a Subway sandwich for $5.99, Akash ordered Momos for $3.99, and Shubham ordered a KFC bucket for $15.99.
You can store these details in a LinkedHashMap for each customer.
LinkedHashMap<String, Object> customerData = new LinkedHashMap<>();
customerData.put("name", "Shubham");
customerData.put("order", "KFC");
customerData.put("price", 15.99);Next, I used LinkedHashMap for tracking menu updates. Suppose you’re managing a dynamic menu where items are added or updated frequently.
You can use LinkedHashMap to store menu items while preserving the order in which they were added. When new items are added, they’ll appear in the order of insertion, making it easier to display an updated menu.
LinkedHashMap<String, Double> menu = new LinkedHashMap<>();
menu.put("Momos", 3.99);
menu.put("KFC Bucket", 15.99);
menu.put("Subway Sandwich", 5.99);Another scenario was organizing a product catalog with details.
Imagine you’re managing a product catalog with various food items, where each item has a set of details like name, type, and price.
A LinkedHashMap can help organize these details effectively.
LinkedHashMap<String, LinkedHashMap<String, Object>> productCatalog = new LinkedHashMap<>();
LinkedHashMap<String, Object> productDetails = new LinkedHashMap<>();
productDetails.put("type", "Momos");
productDetails.put("price", 3.99);
productCatalog.put("Momos", productDetails);I also used LinkedHashMap for tracking ordered events.
Suppose you’re tracking events in the order they occurred—Akash checked out from Subway, Shubham placed an order at KFC, and Priya added Momos to her cart.
A LinkedHashMap can help keep these events in order.
LinkedHashMap<String, String> orderEvents = new LinkedHashMap<>();
orderEvents.put("Event1", "Akash checked out from Subway");
orderEvents.put("Event2", "Shubham placed an order at KFC");
orderEvents.put("Event3", "Priya added Momos to her cart");Another use was in session tracking.
If you’re managing user sessions, LinkedHashMap can help track session activities in the order they occur. This was particularly useful in managing complex workflows where order mattered.
LinkedHashMap<String, String> userSessions = new LinkedHashMap<>();
userSessions.put("Session1", "Login");
userSessions.put("Session2", "Browse Menu");
userSessions.put("Session3", "Add to Cart");I applied LinkedHashMap for organizing discounts too. Suppose you have a set of discounts applied in a particular order. LinkedHashMap allows you to store these discounts while maintaining their application sequence.
This way, when retrieving the discounts, they’ll appear in the order of their application.
LinkedHashMap<String, Double> discounts = new LinkedHashMap<>();
discounts.put("Discount1", 5.0);
discounts.put("Discount2", 10.0);Tracking order status was another real-world application. You can use LinkedHashMap to track the status of an order as it progresses through different stages.
This was incredibly helpful in customer support scenarios where understanding the order of events was crucial.
LinkedHashMap<String, String> orderStatus = new LinkedHashMap<>();
orderStatus.put("Order Received", "Pending");
orderStatus.put("Order Prepared", "In Progress");
orderStatus.put("Order Delivered", "Completed");Managing event logs became easier with LinkedHashMap. Suppose you’re logging various events happening in your system, like a user adding an item to the cart or completing a payment.
LinkedHashMap can help keep these logs in sequence, ensuring that you have a clear timeline of events.
LinkedHashMap<String, String> eventLogs = new LinkedHashMap<>();
eventLogs.put("Log1", "Item added to cart");
eventLogs.put("Log2", "Payment completed");Finally, I used LinkedHashMap for storing user preferences. Suppose you’re handling user preferences like their preferred restaurants or order types.
A LinkedHashMap can help store these preferences while preserving their sequence, making it easier to personalize user experiences.
LinkedHashMap<String, String> userPreferences = new LinkedHashMap<>();
userPreferences.put("Priya", "Subway");
userPreferences.put("Akash", "Momos");
userPreferences.put("Shubham", "KFC");The Eureka Moment
Here’s the basic idea: I used Java’s reflection API to dynamically create an instance of the class and set its fields based on the entries in the LinkedHashMap.
This method allowed me to transform the map into an object, maintaining the structure and data integrity.
LinkedHashMap<String, Object> customerData = new LinkedHashMap<>();
customerData.put("name", "Shubham");
customerData.put("order", "KFC");
customerData.put("price", 15.99);
Customer customer = LinkedHashMapToObject.convertMapToObject(customerData, Customer.class);This approach allowed me to work with the data as if it were a regular Java object, with all the benefits of type safety and IDE support.
Why I Created This Tool
You might be wondering why I went through all this trouble. Why not just stick with the LinkedHashMap? Well, I’ve always believed that code should be as intuitive and straightforward as possible.
By converting a LinkedHashMap to a generic object, I made it easier to handle the data in a structured way, reducing errors and making the code more readable.
It’s like organizing your snacks in a pantry. Sure, you could just throw everything in a bin and dig through it when you’re hungry.
But wouldn’t it be better if you had everything neatly arranged, with Haldiram’s in one section, KFC in another, and Dominos in yet another? That’s the kind of order I was aiming for.
Also this same tools can be used to generate Generic Object from LinkedHashMap. I have used this tools for LinkedHashMap to Custom java class as well.
Since online tools are not available so I have put lot of efforts in creating this conversion tool of linkedHashmap so that you can use it.
Challenges Along the Way
Of course, this journey wasn’t without its challenges. I remember the frustration when I first encountered the dreaded NoSuchFieldException.
It was like ordering a Veggie Delight from Subway and finding out they’re out of veggies.
I had to learn to handle exceptions and edge cases to ensure that my conversion method was robust and could handle any situation thrown at it.
For example, what if the LinkedHashMap contains a key that doesn’t match any field in the class? Or what if the data types don’t align?
These were the kind of scenarios that kept me up at night, but ultimately, solving them made the tool even more versatile.
Real-World Applications
Over the years, I’ve found countless applications for this tool.
Whether it’s transforming user input into structured data for processing or converting configuration settings into objects that can be easily manipulated, the ability to convert LinkedHashMap to a generic object has been a game-changer.
One memorable instance was when I worked on a project that involved integrating different food delivery services into a single platform.
The data from each service—Haldiram’s, KFC, Dominos, and Subway—came in various formats, and I needed a way to standardize it.
Using LinkedHashMap and my conversion tool, I was able to seamlessly integrate and process the data, making the platform user-friendly and efficient.
Lessons Learned
This experience taught me valuable lessons about persistence, the importance of understanding data structures, and the power of Java’s reflection API.
More importantly, it taught me that sometimes, the best solutions come from the most unexpected challenges.
Just like discovering that a combination of Momos and Subway cookies can be strangely satisfying, I learned that embracing complexity can lead to elegant solutions.
Final Thoughts
Looking back, I’m glad I didn’t take the easy way out.
I’m glad I stood my ground, debated with Priya and Akash, and pushed through the challenges.
The tool I created has not only helped me in countless projects but has also become a testament to the importance of perseverance and the pursuit of simplicity in coding.
So, if you ever find yourself in a situation where you need to convert a LinkedHashMap to a generic object in Java, remember my story.
Remember that it’s not just about finding a solution—it’s about creating something that makes your code cleaner, your data more manageable, and your life just a little bit easier.
And who knows? You might even enjoy the process, just like finding joy in the little things—like a perfectly ordered pantry full of your favorite snacks.