Flutter

dart语言中list和map的遍历

2020-08-26  本文已影响0人  小迷糊_dcee

1、list的遍历

var list = [1, 2, 3, 4, 5];
  for (var i = 0; i <= list.length; i++) {
    print(i);
  }

  for (var item in list) {
    print(item);
  }

  list.forEach((element) {
    print(element);
  });

  //where判断大于3,返回值为(4,5),toList()组成新的list
  var newList = list.where((element) => element > 3).toList();
  print(newList);

  //any 判断list的数据是否有大于3的值,返回值为bool,true
  var checkAny = list.any((element) => element > 3);
  print(checkAny);

  //every  判断list里面的数据是否都大于3,返回值为bool, false
  var checkEvery = list.every((element) => element > 3);
  print(checkEvery);

2、map的遍历

var map = {
    "name":"张三",
    "age":22,
    "work":"上班族",
    "sex":"男",
  };


  for(var item in map.keys){
    print(item);
  }

  for(var item in map.values){
    print(item);
  }

  map.forEach((key, value) {
    print("$key---$value");
  });

  
  var newList = map.values.where((element) => element==22);
  print(newList.toList());

  //判断map的值是否有张三,返回值bool
  var checkAny = map.values.any((element) => element=="张三");
  print(checkAny);

  //判断map的值是否全部为张三,返回值bool
  var checkEvery = map.values.every((element) => element=="张三");
  print(checkEvery);

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