Asynchronous Programming

Asynchronous Programming In Dart

Asynchronous Programming is a way of writing code that allows a program to do multiple tasks at the same time. Time consuming operations like fetching data from the internet, writing to a database, reading from a file, and downloading a file can be performed without blocking the main thread of execution.

Synchronous Programming

In Synchronous programming, the program is executed line by line, one at a time. Synchronous operation means a task that needs to be solved before proceeding to the next one.

Example Of Synchronous Programming

void main() {
  print("First Operation"); 
  print("Second Big Operation"); 
  print("Third Operation"); 
  print("Last Operation"); 
}

First Operation
Second Big Operation
Third Operation
Last Operation

Here in this example, you can see that it will print line by line. Let’s suppose Second Big Operation takes 3 seconds to load then Third Operation and Last Operation need to wait for 3 seconds. To solve this issue asynchronous programming is here.

Asynchronous Programming

In Asynchronous programming, program execution continues to the next line without waiting to complete other work. It simply means, Don’t wait. It represents the task that doesn’t need to solve before proceeding to the next one.

Example Of Asynchronous Programming

void main() {
  print("First Operation");   
  Future.delayed(Duration(seconds:3),()=>print('Second Big Operation'));
  print("Third Operation"); 
  print("Last Operation"); 
}

First Operation
Third Operation
Last Operation
Second Big Operation

Here in this example, you can see that it will print Second Big Operation at last. It is taking 3 seconds to load and Third Operation and Last Operation don’t need to wait for 3 seconds. This is the problem solved by Asynchronous Programming. A Future represents a value that is not yet available, you will learn about Future in the next section.

Why We Need Asynchronous

• To Fetch Data From Internet,
• To Write Something to Database,
• To execute a long-time consuming task,
• To Read Data From File, and
• To Download File etc.

Such asynchronous operations usually take a long time to complete, so it usually provide results in the form of a Future. If the result has multiple parts, then it provides as a Stream. You will learn about Future and Stream in the next section.

Important Terms

• Synchronous operation blocks other operations from running until it completes.
• Synchronous function only perform a synchronous operation.
• Asynchronous operation allows other operations to run before it completes.
• Asynchronous function performs at least one asynchronous operation and can also perform synchronous operations.