Gain insights into Dart's object-oriented features, explore extensions, enums, mixins, and asynchronous programming. Discover hands-on code practice to confidently apply Dart in your projects.

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dart2_7

Dart is a fully object-oriented, class-based, simple, and clean language. Google’s popular mobile framework, Flutter uses Dart language to implement high-quality native applications, so it’s recommended that you understand Flutter before beginning this course.

In this course, you will dive deep into Dart 2 language features while using interactive hands-on code playgrounds. This course will help you become confident with Dart extensions, enums, mixins, generics, libraries, asynchronous programming, class variables, callable classes, and generator functions.

By the end of this course, you will have a strong understanding of Dart principles, and you’ll be ready to start using this powerful language in your own projects.

Developing Web Applications with Dart

# Single Subscription Stream Operations

In this lesson, you will learn the usage of a Stream's methods and properties with the help of examples. We will be using the following sample stream to carry out these operations:

**Sample Stream:**

We will use the following Stream to demonstrate the upcoming examples of Stream operations.
This function creates a Stream of numbers from 1 to the `last` number passed into.
```
//This will generate a stream and return a reference to it.
Stream<int> createNumberStream(int last) async* {
  for (int i = 1; i <= last; i++) {
    yield i; //to be able to send spaced out events
  }
}
```

## Using the `where()` Method

Let's see an example to find and print a number greater than 3 in a number stream generated using `createNumberStream(5)`.

In this example, the [`where`](https://api.flutter.dev/flutter/dart-async/Stream/where.html) method is called on the Stream and a `listen()` method is chained to the stream which acts as a callback. When a number meeting the criteria is found, it is sent over to callback to take further action on it. In the `where` block, any number greater than 3 is printed on the console.

The `fileterUsingWhere()` function demonstrates the usage of the `where` method to filter the numbers which are greater than 3. 

In the Stream of numbers from 1 through 5, two numbers, 4 and 5, are greater than 3.

Let's dive into Single Subscription Stream Operations.

Introduction

Dart Extensions

Dart Enums

Dart Mixins

Dart Generics

Dart Libraries

Asynchronous Programming In Dart

Miscellaneous

Next Steps

Single Subscription Stream Operations

Single Subscription Stream Operations