Discovering the "difference" Method in Dart

Tip for boost your Flutter or any other Dart SDK productivity.

In Dart, "difference" is a method that can be used with sets to compute the difference between two sets. In other words, it helps you identify elements present in one set but not in another.

As the facts say more than a thousand words, I allow myself to show you through these examples of use, the potential of "difference", and illustrate part of what you can get out of it:

• Removing Duplicates

Imagine we're working on an app that manages lists of unique elements. We want to ensure there are no duplicate elements in a list before displaying it. This is where "difference" shines:

Set<int> list1 = {1, 2, 3, 4};
Set<int> list2 = {3, 4, 5, 6};

Set<int> difference = list1.difference(list2);

log(difference); // Output: {1, 2}        

• Identifying Unique Elements

Now, let's consider a scenario where we want to identify unique songs in a music playlist:

Set<String> playlist = {"Song 1", "Song 2", "Song 3"};
Set<String> history = {"Song 2", "Song 4", "Song 5"};

Set<String> uniqueInPlaylist = playlist.difference(history);

log(uniqueInPlaylist); // Output: {"Song 1", "Song 3"}        

Using "difference," we've found the songs present in the playlist but not in the history, providing us with {"Song 1", "Song 3"}. This is useful for showcasing new additions to the playlist.

• Efficiently Adding Unique Elements

Consider a situation where we want to add unique elements from one list to another:

List<String> newValues = ["A", "B", "C"];
List<String> values = ["B", "C", "D", "F"];        

Use this...

newValues.addAll(Set<String>.from(values).difference(Set<String>.from(newValues)));

log(newValues); // Output: ["A", "B", "C", "D", "F"]        

Instead of something like this...

for (var i = 0; i < values.length; i++) {
    if (!newValues.contains(values[i])) {
        newValues.add(values[i]);
    }
}

log(newValues); // Output: ["A", "B", "C", "D", "F"]        

or this loop...

for (final value in values) {
   if (!newValues.contains(value)) newValues.add(value);
}

log(newValues); // Output: ["A", "B", "C", "D", "F"]        

In this scenario, we've efficiently added unique elements from 'values' to 'newValues' using the "difference" method. It not only simplifies the code but also ensures that no duplicates are introduced.

Advantages of Using "difference":

• Simplicity: The "difference" method simplifies the task of finding differences between sets, saving time and reducing code complexity.
• Performance: Compared to manual approaches involving loops, "difference" is more efficient in terms of performance, especially with large sets.

Have you ever used the "difference" method in Dart? Do you have other interesting examples to share? I look forward to your comments and experiences.

#Dart #Flutter #AppDevelopment #Android #iOS #FlutterWeb