When I started this morning, I opened my code editor, created a new Dart file, and began experimenting. I told myself, “No new topics today, only practice.”

Lists

I began with lists, the most familiar of all. Lists are ordered, allow duplicates, and are great for storing groups of data. I created different types of lists, one with strings, another with integers, and even one with mixed data.

I practiced adding new items with .add() and .insert(), updating elements using their index, and removing elements using .remove() and .removeAt(). Then, I tried sorting and reversing lists to better understand how Dart organises data.

Here’s one of my exercises:

List<int> numbers = [5, 3, 9, 1, 5];
numbers.sort();
print(numbers); // [1, 3, 5, 5, 9]
print(numbers.reversed.toList()); // [9, 5, 5, 3, 1]

This simple test showed me how easy it is to control data flow in Dart. I also noticed that lists are perfect when you care about order, like when displaying items in a certain sequence or saving scores by round.

Sets

After that, I moved on to sets. At first, sets felt a lot like lists, but then I realised how unique they are. Sets do not allow duplicates, and they don’t keep order. They’re great when you only want unique values.

I created a few sets and played with operations like adding, removing, and comparing them. What really stood out were the set operations: union, intersection, and difference. These are extremely powerful when working with data comparisons.

Here’s an example I ran:

Set<int> setA = {1, 2, 3, 4};
Set<int> setB = {3, 4, 5, 6};

print(setA.union(setB));        // {1, 2, 3, 4, 5, 6}
print(setA.intersection(setB)); // {3, 4}
print(setA.difference(setB));   // {1, 2}

I could clearly see how sets can be used for filtering unique data or finding shared items between two groups. They’re also faster to search through than lists, especially when dealing with large amounts of data.

Maps

Finally, I spent the rest of my time working on maps. Maps are like little dictionaries in Dart. Each item is stored as a key-value pair, where the key must be unique.

Maps are great when you need to link one piece of data to another, like names to scores, product IDs to details, or countries to their capitals.

Here’s one of my practice codes:

Map<String, int> scores = {
  'Alice': 90,
  'Bob': 85,
  'Clara': 92
};

scores['David'] = 88;  // Add a new entry
scores['Alice'] = 95;  // Update Alice's score

scores.forEach((key, value) {
  print('$key scored $value');
});

I loved how easy it was to loop through a map and access both keys and values. It felt like working with JSON data, which means this concept will be super useful later when I start handling APIs or saving user data.

To test myself, I tried a small program that used lists, sets, and maps together.

Here’s what I did:

• I stored names in a list.

• I converted that list into a set to remove duplicates.

• Then I created a map that linked each unique name to a score.

List<String> names = ['Alice', 'Bob', 'Alice', 'Clara'];
Set<String> uniqueNames = names.toSet();

Map<String, int> scoreMap = {};
int score = 80;

for (var name in uniqueNames) {
  scoreMap[name] = score;
  score += 5;
}

print(scoreMap);

Output:

{Alice: 80, Bob: 85, Clara: 90}

This simple practice made me see how all three collections can work together to solve real problems, clean data, organise it, and give it meaning.

Today was not about learning something new, but about building confidence in what I’ve already learned. Practicing lists, sets, and maps helped me understand the differences between them:

• Lists are for ordered data.

• Sets are for unique items.

• Maps are for key-value pairs.

Each one has its own use, and now I can easily decide which to use depending on the problem I’m solving.

Next Step

Tomorrow, I’ll start exploring more advanced concepts, maybe higher-order functions, collection methods, or even working with data transformations in Dart. I’m proud of how far I’ve come in just 16 days. Each step makes Dart feel easier and more natural.

Join Me!

I’ll be sharing my progress every week here on Hashnode.

You can connect with me on Twitter(X), Instagram, Linkedin, and Facebook.

If you’re also learning Dart or Flutter, let’s connect . I’d love to learn together!

the previous days are available my medium.