Dart Map key value pair collection example

dart_map_example.dart

main() {
  Map map = {
    'key1': 'value1',
    'key2': 'value2',
    'key3': 'value3'
  };
 
  print('map.length is ${map.length}');
  print('map: $map');
  print('map[\'key1\'] is ${map['key1']}');
  print('map[\'test\'] is ${map['test']}\n');
 
  //Add a new value
  map['key4'] = 'value4';
  print('map.length is ${map.length}');
  print('map: $map\n');
 
  //Check if a key is present
  print('map.containsKey(\'value1\'): ${map.containsKey('value1')}');
  print('map.containsKey(\'key3\'): ${map.containsKey('key3')}\n');
 
  //List entries, keys and values
  print('map.entries: ${map.entries}');
  print('map.keys: ${map.keys}');
  print('map.values: ${map.values}');
}