Dart Collectons Datatypes

collection is a variable it can save many data for example

List
Set
Mapping

List Example

List index is start from 0

['this str', 10, 15, 2.0]

example this str is index 0 and 10 is index 1, etc

void main() {
  List datas = ['this str', 10, 15, 2.0];
  print(datas);
 }

Getting All List item

for print all item you can use looping

void main() {
  List datas = ['this str', 10, 15, 2.0];
  
  // print all list
  for (int i = 0;  i < datas.length; i++) {
    print(datas[i]);
  }
 }

if using forEach

void main() {
  List datas = ['this str', 10, 15, 2.0];
  int i = 0;
  datas.forEach((item) {
    print('data ke ${i+1} isi data ${item}');
    i++;
  });
}

pythonic way using for in

void main() {
  List datas = ['this str', 10, 15, 2.0];
  int i = 0;
 
  for (dynamic data in datas) {
    print("data index ${i} ${data}");
    i++; // <- index
  }
  
  print("Total Data: ${datas.length}");

}

Set

Set is a immutable datatype

void main(List<String> args) {
  Set <String> halogens = {'fluorine', 'chlorine', 'bromine', 'iodine', 'astatine'};
}

Concate the Set

We Can Concate the Set Datatype but can’t duplicate the Data

void main() {
  Set dummies = {10, 15, 9, 8, 7};
  Set dummy = {1, 5, 19, 8, 7};
  
  print(dummies.union(dummy));

}

// result
{10, 15, 9, 8, 7, 1, 5, 19}

Map

map is a data type that has a key and a value

var gifts = {
  // Key:    Value
  'first': 'partridge',
  'second': 'turtledoves',
  'fifth': 'golden rings'
};

var nobleGases = {
  2: 'helium',
  10: 'neon',
  18: 'argon',
};

another example

 Map scores = {
    "math": {10, 15, 9, 8, 7},
    "social": {1, 5, 19, 8, 7}
};

{math: {10, 15, 9, 8, 7}, social: {1, 5, 19, 8, 7}}

Manual Mapping

manual mapping using looping

main(List<String> args) {
  List<String> dataList = [];
  List<int> number = [10, 20, 30, 60];

  // looping
  number.forEach((element) {
    dataList.add('angka ke ' + element.toString());
  });

  // cetak list
  dataList.forEach((newElement) {
    print(newElement);
  });
}

Using Map Function

This is Best Practice for Mapping Data using map() function

main(List<String> args) {
  List<String> dataList = [];
  List<int> number = [10, 20, 30, 60];

  // looping
  number.map((e) => ' angka ' + e.toString());

  // cetak list
  dataList.forEach((newElement) {
    print(newElement);
  });
}

Conclusion

The Important DataType for Developing Software Applications is A Collection Datatype it can be used for Get Response data From API or Mapping to Display in Mobile Applications.