I am very new to `Flutter`, and stuck at the following problem:

```dart
  child: RaisedButton(
   onPressed: () {
   fetchData();
  },
  // ...
  fetchData() async {
    final res = await http.get("https://jsonplaceholder.typicode.com/posts");
    if (res.statusCode == 200) {
      // If the call to the server was successful, parse the JSON
      print("it works");
      return json.decode(res.body);
    } else {
      // If that call was not successful, throw an error.
      throw Exception('Failed to load post');
    }
  }
  // ...

```

when i remove the http.get part it prints "it works" so i think the problem is in the http.get executing.