[Dart] Manipulate Lists/Arrays in Dart

We will learn how to work with Lists using a variety of methods made available in the dart:core library. We will explore the top methods for working with List type collections.

Learn more about Lists at https://api.dartlang.org/stable/2.2.0/dart-core/List-class.html

Array to list:

because .map return iterable.

  var fruits = ['banana', 'pineapple', 'orange', 'watermelon', 'apple'];

  var fiboNumbers = [, , , , , , ];

  List<Map<String, dynamic>> users = [

    { 'name': 'John', 'age':  },

    { 'name': 'Jane', 'age':  },

    { 'name': 'Mary', 'age':  },

  ];

    // array to list

    var mappedFruits = fruits.map((fruit) => 'I love $fruit').toList();

    print(mappedFruits);

reduce vs fold:

reduce: doesn't provide the init value, but 'fold' does:

  const initialValue = ;

  var sum2 = fiboNumbers.fold(initialValue, (curr, next) => curr + next);

  print( sum2 );

  var sum = fiboNumbers.reduce((curr, next) => curr + next);

  print( sum );

filtering:

  var over21s = users.where((user) => user['age'] > );

  print( over21s.length );

  var nameJ = users.firstWhere((user) => user['name'].startsWith('J'), orElse: () => null);

  print( nameJ );

  var under18 = users.singleWhere((user) => user['age'] < , orElse: () => {'error': 'Not Found'});

  print( under18 );

take & skip:

  print( fiboNumbers.take().toList() );

  print( fiboNumbers.skip().toList() );

  print( fiboNumbers.take().skip().take().toList() );

expend: the same as flatMap in JS

  var flattened = [[, ], [, ]].expand((pair) => pair).toList();

  print( flattened );

  var duplicated = fiboNumbers.expand((i) => [i, i]).toList();

  print( duplicated );

巴特西

[Dart] Manipulate Lists/Arrays in Dart

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