Dart语言中如何判断一个字符串能否被解析为json

在php中我们可以用如下方法判断一个字符串能不能被解析为json

/**
* 是不是json
* @param $string
* @return bool
*/
function is_json($string) {
    json_decode($string);
    return (json_last_error() == JSON_ERROR_NONE);
}

dart中就麻烦了些

import 'dart:convert';
void main() {
  var jsonString = '{"abc';
  Map<String,dynamic> decodedJSON;
  var decodeSucceeded = false;
  try {
    var x = json.decode(jsonString) as Map<String, dynamic>;
    decodeSucceeded = true;
  } on FormatException catch (e) {
    print('The provided string is not valid JSON');
  }
  print('Decoding succeeded: $decodeSucceeded');
}