Imports

A library in a programming language represents a collection of routines (set of programming instructions).

1. Core libraries

Dart has a rich set of core libraries that provide essentials for many everyday programming tasks such as working on collections of objects (dart:collection), making calculations (dart:math), and encoding/decoding data (dart:convert). Additional APIs are available in community contributed packages.




The Dart core libraries that work on all Dart platforms:

    Dart:async : Support for asynchronous programming, with classes such as Future and Stream.

    Dart:collection : Classes and utilities that supplement the collection support in dart:core.

    Dart:convert : Encoders and decoders for converting between different data representations.

    Dart:core : Built-in types, collections, and other core functionality for every Dart program.

    Dart:developer : Interaction with developer tools such as the debugger and inspector.

    Dart:math : Mathematical constants and functions, plus a random number generator.

    Dart:typed_data : Lists that efficiently handle fixed sized data (for example, unsigned 8-byte integers) and SIMD numeric types.




Example:

import 'dart:math';

 

void main() {

  print(cos(0.5));

  print(e);

  print(min(13 * 12, 11 * 14));

}






0.8775825618903728
2.718281828459045
154





For more about the math library : Dart:Math




If you import two libraries that have conflicting identifiers, then you can specify a prefix for one or both libraries using "as".

Example:

import 'dart:math' as math;

 

void main() {

  print(math.sin(0.5));

  print(math.exp(4));

}






0.479425538604203
54.598150033144236



2. Importing Custom Libraries

Dart also allows you to use your own code as a library.

Example:

File 1 :

import 'dart:math';

 

void printmax(int x, int y) {

  print("the max is ${max(x, y)}");

}

 

void printmin(int x, int y) {

  print("the min is ${min(x, y)}");

}






The main file in the same directory:

import 'file1.dart';

 

void main() {

  int a = 34, b = 50;

  printmax(a, b);

  printmin(a, b);

}






the max is 50
the min is 34





Note:

If the two files are not within the same directory, we need to add the path:


import 'dir/library_name' ;