A **future** is a valuable construct that allows *asynchronous programming* in Dart. **Asynchronous programming** is programming that caters to delayed operations. These delayed operations happen when you need to fetch data over a server, write to a database, or read a file on the system (commonly referred to as I/O operations). 
> With asynchronous programming, you can tell your computer that it is free to perform other operations while the asynchronous operation completes.

// Function that replicates a slow operation
Future<void> getOrder(){
    Future.delayed(
    Duration(seconds: 2), () =>
      print("Vanilla Shot"));
}

void main() {
  getOrder();
  
  //Notice how the following appears on screen first
  print("Getting order...");  
   
  
}




# What is a future?

A future is an instance of the Future class. It can have two states: *uncompleted* or *completed*.

## Uncompleted 
When a future is called, but has not returned a value, the future is in the uncompleted state.

Future<String> getOrder(){
  Future.delayed(
    Duration(seconds: 2), () 
    => 'vanilla shot');
}

void main() {
  var order = getOrder();
  print("Getting order...");  
  print(order); 
  
}




## **Completed**
If the asynchronous call is successful, the future completes with a *value*. Otherwise, it completes with an *error*.

 
Future<String> getOrder(){
  return Future.delayed(
    Duration(seconds: 2), () 
    => 'vanilla shot');
}

void main() async {
  var order = getOrder();
  print("Getting order...");  
  print(await order);
  
}


> Read more about getting a program to wait using async/await, [here](https://www.educative.io/answers/darts-async-await-in-flutter).

### a. Completing with a value
If successful, a future of type `Future<String>` will return a `String` value. Similarly, `Future<T>` (a future with any valid type `T`) will return `T`.

### b. Completing with an error
If unsuccessful, a future will return an error.



// Function that replicates an error 
Future<void> getOrder(){
  Future.delayed(
    Duration(seconds: 2), () 
    => throw Exception('Some Error'));
}

void main() {

  getOrder();
  print("Getting order...");  
   
  
}


>Read more about asynchronous programming in Dart in the [official documentation](https://dart.dev/codelabs/async-await).


      

What are Dart futures?

A future is a valuable construct that allows asynchronous programming in Dart. Asynchronous programming is programming that caters to delayed operations. These delayed operations happen when you need to fetch data over a server, write to a database, or read a file on the system (commonly referred to as I/O operations).  With asynchronous programming, you can tell your computer that it is free to perform other operations while the asynchronous operation completes.  