#  
#   

In [Dart](https://www.educative.io/answers/what-is-dart), we can execute asynchronous code by using a variety of classes and keywords such as `Future`. 
A `Future` allows us to execute asynchronous programs.

> **Note:** A program code can accomplish tasks while awaiting the completion of another action thanks to asynchronous operations. 

A `Future` primarily represents the outcome of an asynchronous operation.

An asynchronous operation includes the following:

1. Fetching data via a network
2. Writing/reading files from cloud storage

In Dart, a `Future` has two states:
1. **Completed:** When an asynchronous operation on a `Future` is finished, the `Future` successfully completes with a value. Otherwise, it completes unsuccessfully with an error.
 
2. **Uncompleted:** When an asynchronous operation is called, it queues up and returns an unfinished `Future`.

> **Note:** In Dart, the state of a `Future` before it has generated a value is referred to as being **uncompleted**.

#    
#  Syntax
```
Future<T>
```
## 
## Return type

The return type is void if the `Future` does not yield any value.


## 
## Code

The following code shows how to use `Future` in Dart.

## Example 1

// getWriterName function of type `Future` which computes a future
// the return type is String
Future<String> getWriterName() {
   // 3 seconds delay to simulate a call to cloud storage or db
   return Future.delayed(Duration(seconds: 3), () => "Maria Elijah");
}


void main() {
   print('Welcome to Educative!');
   var writerName = getWriterName();
   // create a callback
   writerName.then((name) => print("The writer's name is $name"));
   print('Keep Learning!');
}



## Code explanation

**Line 3-6:** We create a function called `getWriterName()` of the `Future` type. This function computes a `Future` and returns a `String`.

**Line 9:** We define the `main()` function.

**Line 10:** We use `print()` to display a statement.

**Line 11:** We assign the `getWriterName()` function to a new variable called `writername`.

**Line 13:** We create a `callback` to display the `Future` value (in our case, the value is the writer's name).

**Line 14:** We use `print()` to display a statement.

> **Note:** The `print()` function on line 14 was executed before the `callback` because the `getWriterName()` function is an asynchronous operation.



// displayGreetings function of type `Future` which computes a future
// the return type is void
Future<void> displayGreetings() {
   // 3 seconds delay to simulate a call to cloud storage or db
   return Future.delayed(Duration(seconds: 3), () => print('Welcome to Educative!'));
}


void main() {
  // call the future 
  displayGreetings();
  print('Keep Learning!');
}

## Code explanation

**Line 4-7:** We create a function called `displayGreetings()` of the `Future` type. This function computes a `Future` and returns `void`.

**Line 10:** We define the `main()` function.

**Line 11:** We call the `displayGreetings()` function.

**Line 13:** We use `print()` to display a statement.



What is Future<> in Dart?

Asynchronous code in Dart uses the Future class to handle tasks that complete in two states: completed or uncompleted.

What is Future<> in Dart?

Syntax

Return type

Code

Example 1

Code explanation

Example 2

Code explanation