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How to do Asynchronous Programming in Flutter with Dart

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Renjith Raj,Chief Technology Officer

‘The sooner you build and execute, the better the applications get’ - SayOne Flutter Team 

Asynchronous programming is a form of parallel execution that fastens up the chain of events in a programming cycle. And Dart is the perfect match for Flutter in many ways, even for asynchronous programming. Although Dart is single threaded, it can interact with other codes that run in separate threads. The use of synchronous code in Dart can possibly cause delay and block your entire program execution. But asynchronous programming solves this issue. And this leads to improved application performance and application responsiveness. 

For these benefits, our Flutter team began doing asynchronous programming in Flutter with Dart. 

Read more: Top 4 Reasons behind Flutter Mobile App Development Popularity

Read more: Flutter vs React Native - The framework you should choose in 2020

Asynchronous Programming in Flutter with Dart 

You need to understand the beginning first in order to predict the end. Likewise, let us understand the basics first to deep-dive into the concept: 

Async functions

Functions form the base of asynchronous programming. These async functions have async modifiers in their body. Here is an example of a general async function below: 

When an async function is called, a Future is immediately returned and the body of the function is executed later. As the body of the async function is executed, the Future returned by the function call will be completed along with its result. In the above example, calling demo() results in a Future. 

Also read: How Much Does It Cost to Develop and Maintain a Flutter App?


When an async function is called, the immediate result is a Future. It is a means of getting a value for the function called, sometime later in the future. In plain words, we can say that a Future is a cue to obtaining the result. 

When a function that returns a Future is requested, these action items happen: 
The work to be done is queued up by the function and the output is an uncompleted Future object.

Later, when a value is available, the Future object completes with that value. 

Putting it together, we get:

Here, the Output is: 
Async Test

Await expressions

Await expressions makes you write the asynchronous code almost as if it were synchronous. In general, an await expression has the form as given below: 

await e

where e is a unary expression. Typically, e is an asynchronous computation and is expected to evaluate to a Future. The await expressions evaluate e, and then suspends the currently running function until the result is ready–that is, until the Future has completed. The result of the await expression is the completion of the Future.

Putting it all together, we get:


Do you want to learn more about the concept? Check our GitHub repository! 

Read more: Why we chose Flutter for Mobile App Development?


During our 7 years of App Development marathon, we have always strived to get the best results for our customers. For this reason, we are keen to learn new technologies, coding methodologies and make the most out of those. Now, asynchronous programming with Dart has become our go-to solution for faster experimentation and results. Get in touch for a FREE consultation on how Flutter can help realize your business product.


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