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Dart 基础语法

List数组操作

firstWhere 方法
Dart 官网 示例

void main() {
  const items = ['Salad', 'Popcorn', 'Toast', 'Lasagne'];

  // You can find with a simple expression:
  var foundItem1 = items.firstWhere((item) => item.length > 5);
  print(foundItem1);

  // Or try using a function block:
  var foundItem2 = items.firstWhere((item) {
    return item.length > 5;
  });
  print(foundItem2);

  // Or even pass in a function reference:
  var foundItem3 = items.firstWhere(predicate);
  print(foundItem3);

  // You can also use an `orElse` function in case no value is found!
  var foundItem4 = items.firstWhere(
    (item) => item.length > 10,
    orElse: () => 'None!',
  );
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every、 any方法

void main() {
  const items = ['Salad', 'Popcorn', 'Toast'];
// // 只要集合里面有满足条件的就返回true
  if (items.any((item) => item.contains('a'))) {
    print('At least one item contains "a"');
  }
// every 每一个都满足条件返回true 否则返回false
  if (items.every((item) => item.length >= 5)) {
    print('All items have length >= 5');
  }
}

items .fillRange(1, 2,'aaa');// 修改了 , 'Popcorn',  值为 aaa
items .fillRange(1, 3,'报不报');// 修改了 'Popcorn', 'Toast'] 值为"报不报"

items .join(',')// 'list 转为字符串 Salad', 'Popcorn', 'Toast'
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