Flutter Map常用操作方法总结

// 使用 {} 创建 Map
var myMap = {
  'key1': 'value1',
  'key2': 'value2',
  'key3': 'value3',
};

// 使用 Map.from() 创建 Map
var myMap = Map.from([
  ['key1', 'value1'],
  ['key2', 'value2'],
  ['key3', 'value3'],
]);

myMap['key4'] = 'value4';
myMap.put('key5', 'value5');

var value = myMap['key1']; // value = 'value1'

myMap.remove('key2'); // 删除键为 'key2' 的元素
myMap.clear(); // 清空所有元素

for (var key in myMap.keys) {
  print('${key}: ${myMap[key]}');
}

for (var key in myMap.keys) {
  print('${key}: ${myMap.values.firstWhere((value) => value == myMap[key])}');
   // 使用 values 遍历找到对应的值并输出，可能会效率低下，不建议频繁使用此操作。
}

void main() {  
  var map = {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'};  
    
  for (var entry in map.entries) {  
    print('Key: ${entry.key}, Value: ${entry.value}');  
  }  
}

var entry = map.firstEntry; // 获取第一个元素  
print('Key: ${entry.key}, Value: ${entry.value}');

var map = {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'};
var lastEntry = map.lastEntry;
print('Key: ${lastEntry.key}, Value: ${lastEntry.value}');

var map = {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'};
var singleEntry = map.singleEntry;
if (singleEntry != null) {
  print('Key: ${singleEntry.key}, Value: ${singleEntry.value}');
} else {
  print('Map is empty or contains multiple entries.');
}

void main() {  
  var map = {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'};  
    
  map.forEach((key, value) {  
    print('Key: $key, Value: $value');  
  });  
}

void main() {  
  var map = {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'};  
    
  for (var entry in map.entries) {  
    print('Key: ${entry.key}, Value: ${entry.value}');  
  }  
}

void main() {  
  var map = {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'};  
    
  for (var entry in map.entries) {  
    print('Key: ${entry.key}, Value: ${entry.value}');  
  }  
}