【Flutter/Dart】Mapクラスの基本的な使い方/基礎から実践

//基本的なMap
var Map名 = Map<キーの型, 値の型>();

//例型を宣言したMap
var fruit = <String, String>();

//基本的な宣言
var Map名 = {
  キー1: 値1,
  キー2: 値2,
  キー3: 値3,
};

//変数に入れる
var ages = {
  'Alex': 18,
  'Ben': 15,
  'Charlie': 25,
};

void main(){

Map<String, String> map = {
'name': 'alex',
'age': '20'
};
print(map['name']);
  }

//出力
//alex

void main(){
  var ages = {
  'Alex': 18,
  'Ben': 15,
  'Charlie': 25,
};
print(ages['Alex']);
  }

void main(){
  var ages = {
  'Alex': 18,
  'Ben': 15,
  'Charlie': 25,
};

ages['Alex'] = 30;
print(ages['Alex']); 
  }

void main(){
  Map<String, int> ages = {
  'Alex': 18,
  'Ben': 15,
  'Charlie': 25,
};
print(ages.isEmpty); 
  }

void main(){
  Map<String, int> ages = {
  'Alex': 18,
  'Ben': 15,
  'Charly': 25,
};
print(ages.length);
  }

void main(){
  final planets = <num, String>{1: 'Mercury', 2: 'Venus', 3: 'Earth', 4: 'Mars'};
final mapFrom = Map<int, String>.from(planets);
print(mapFrom);
  }

void main(){
  var ages = {
  'Alex': 18,
  'Ben': 15,
  'Charly': 25,
};

var Dakota = {'Dakota':24};

ages.addAll(Dakota);
print(ages);}

//map1とmap2を結合した新しいMapを 
var merge = {}..addAll(map1)..addAll(map2);

　//map1とmap2を結合
var merge = {
    ...map1,
    ...map2,
}

型 toJson() => {名前つき引数:データ};

Map<String, dynamic> toJSON() {
  return <String, dynamic>{
    'text': text,
    'selectionBase': selection.baseOffset,
    'selectionExtent': selection.extentOffset,
    'selectionAffinity': selection.affinity.toString(),
    'selectionIsDirectional': selection.isDirectional,
    'composingBase': composing.start,
    'composingExtent': composing.end,
  };
}
void main(){
print(Map);
}