DART MIXINS Mixins are a way of reusing a class’s code in multiple class hierarchies.
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DART Static // to make any variable universal for all object belongs to that class // static is also applied to method of class // static work without any constructor int main(){ // Square myShape = Square(); not need constructor static int side = Square. noOfSide ; print(side) ; // Circle().getOurCircumference(radius: 20); // without static Circle. getOurCircumference (radius: 20 ) ; // with static, call by this // static work without any constructor as we seen above } class Square{ static int noOfSide = 4 ; } class Circle{ static const double pi = 3.1415926 ; static void getOurCircumference ({double radius}){ double circumference = 2 * pi * radius ; print(circumference) ; } }
[ Dart ] Loops Type-1 void main () { buyMilk( 7 ) ; } void buyMilk (int days) { for (int i = 1 ; i <= days ; i++) { print( 'Buying milk on day $i ' ) ; } } Type-2 Example List<String> fruits = [ 'Apple' , 'Mango' , 'Banana' , 'Strawberry' , 'Grapes' ] ; void main(){ pieMaker() ; } void pieMaker (){ for (String fruit in fruits){ print(fruit + ' Pie' ) ; } } Example List<int> winningNumbers = [ 12 , 6 , 34 , 22 , 41 , 9 ] ; void main(){ List<int> ticket1 = [ 45 , 2 , 9 , 18 , 12 , 33 ] ; List<int> ticket2 = [ 41 , 17 , 26 , 7 , 35 , 32 ] ; checkNumber(ticket1) ; } void checkNumber (List<int> myNumber){ int match = 0 ; for (int myNum in myNumber){ for (int winNum in winningNumbers){ if (myNum == winNum){ match++ ; } } } print( 'Got a $match matches' ) ; }
DART EXCEPTION HANDLING PARSING Change string value to double void main (){ String myString = 'abc' ; double myStringAsdouble = double. parse (myString) ; print(myStringAsdouble + 56 ) ; } Used example in a program how to use try and catch Catch takes the error and print in flutter terminal as written in code @override Widget build (BuildContext context) { String myString = "abc" ; double margin ; try { margin = double. parse (myString) ; } catch (e) { print(e) ; margin = 30 ; // use this or } return Scaffold ( body: Container ( margin: EdgeInsets . all (margin ?? 30 ) , // or use this color: Colors. grey , ) , ) ; } when margin takes value as 'abc' but it cant be converted into double so app return error message like below so we also give new margin value so that instead of that ('abc'), new value is used in a container DART NULL AWARE OPERATOR As above we use margin ??...