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why print statement not executing while placing inside map in flutter

I am learning list and here i have created a simple demo for traversing all numbers of list using map…

according to me it should print ‘okay’ 9 times as i have nine integer inside a list
and another new thing is that if i print this list named x after this line of code..it works which i have commented.

final List<int>  numbers=[10,20,30,40,50,60,70,80,90];

final x=numbers.where((element) {
  print('Okay');
  return element>50;
});

// if i print x it will show hello
print(x);
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2

Answers


  1. 0

    void main() {
    final List numbers = [10, 20, 30, 40, 50, 60, 70, 80, 90];

    // Using where to filter numbers greater than 50
final x = numbers.where((element) {
    print('Okay'); // This will execute for each element being checked
    return element > 50;
});

// Force evaluation by converting to a list
final filteredNumbers = x.toList(); 

// Print the filtered numbers
print(filteredNumbers); // Will show: [60, 70, 80, 90]

    }

    his code is a straightforward demonstration of filtering data in Dart using built-in collection methods, showcasing important programming principles applicable across various languages. For further details on Dart’s collection methods and their usage, you can refer to the official Dart documentation.

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  2. 0

    [ where ] method in Dart returns a lazy iterable
    Okay only executed when you start iterating over x

    final List<int> numbers = [10, 20, 30, 40, 50, 60, 70, 80, 90];

final x = numbers.where((element) {
  print('Okay');
  return element > 50;
}).toList(); // Convert the iterable to a List

print(x); // This will print [60, 70, 80, 90]

    toList() method forces the iteration of the [where] clause which causing the print(‘Okay’) statement to execute 9 times.

    Hope it will help

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