Dart notes:

1- using final and const with data collection 

you cannot modify data collection "Set,List,and Map'  if it is const .
example:

 const List empList = ['Tarek','Ali','Hamed']; 

 empList.add('Adel'); // Error in correct

 empList = ['Hani']; // error In correct 

 However , with final there is a difference. You can modify a final List ,Set,Map using only add or addAll method. 

example :

 final List empList = ['Tarek','Ali','Hamed']; 

 empList.add('Hani'); // correct

 empList.addAll(list2); //correct 

  2- Switch case

used to test literal value. 
example: 

String name = 'Ramy'; Switch(name) { 

 case 'rami': print(false); 

 case 'RamY': print(false); 

 case 'Ramy' : print(true); 

 default: print('not valid'); 

 } 

 In dart, you do not have to use break, it will break automatically.Unlike java, if condition evaluated true,statment will be executed and execution will be exited. 

  3- handling exceptions 

 In dart, syntax is different. 
example: 

 try{ 

 // code 

   on(NoSuchMethodError){ 

    // handle the exception 

 } catch(err){ print($err); 

 } 

}

4-functions

use [] to mark parameters as optional. example:

    void add([int n1,int n2,int n3,int n4]){
            ////code
        }

use {} to make named parameter and optional too. example

            void add({int n1, int n2, int n3}){
                    // code
        }

arrow function

 the sign    =>  means return. 

example:

   int add(int num1, int num2)=> num1+num2;

5-Constructors

To declare named constructor , use dot operator. example

Device.laptop(int ram, num size , String model , String color){}

6- Access Modifiers

 Do not write public or private word. they are not key words in dart.

All attributes and method within a class are public by default.

To make attribute private use undescore before the name. example.

class CustomerAccount{

  String customerName;

  String? nationalId;

  String? _creditCardNumber; // this is declared private

}