Edit the Outer Variable With the Class Constructor

how do i edit the chattile variable in the contructor 'tambah' as shown below:

class ChatCardList extends StatefulWidget
List<ChatTile> chattile; //EDIT THIS
ChatCardList(Key key, this.chattile) : super(key: key);
Future<void> _onSocketInfo_newMessage(dynamic data) async
ChatCardList _data = new ChatCardList.tambah(data);


ChatCardList.tambah(String message)
print("PESAN BARU : " + message);
this.chattile.add(message); //PUSH OBJECT

print(chattile); //notting added
@override
_ChatCardListState createState() => new _ChatCardListState(chattile:chattile);



why did that happen? is my script wrong, or is there something missing from my code?

many thanks,

1 Answer
1

Could you go back and check that this is the actual code that is causing your problem.
The code displayed here will not compile at all, so it's hard to say where the real problem is. Alternatively, describe in detail what you are actually trying to achieve.

The ChatCardList.tambah(String message) { constructor does not initialize chattile, so the value of this.chattile in the body should be null. Calling add on that will throw. Otherwise that code is perfectly fine, it is how you add to a list stored in this's chattile variable.

ChatCardList.tambah(String message) {

chattile

this.chattile

null

add

this

chattile

The Future<void> _onSocketInfo_newMessage(dynamic data) async { method creates a new ChatCardList using CharCardList.tambah, but never does anything with it (it doesn't return the value), so nobody will ever see that object or its chattile value.

Future<void> _onSocketInfo_newMessage(dynamic data) async {

ChatCardList

CharCardList.tambah

chattile

Also, the print(chattile); code is outside of any function or constructor body, so it is really declaring an abstract method called print which takes a parameter named chattile. Since your class isn't abstract, that should cause a compile-time error.

print(chattile);

print

chattile

So, one way to rewrite your program could be:

class ChatCardList extends StatefulWidget
List<ChatTile> chattile; //EDIT THIS
ChatCardList(Key key, this.chattile) : super(key: key);
Future<void> _onSocketInfo_newMessage(dynamic data)
String message = data;
this.chattile.add(message);


@override
_ChatCardListState createState() => new _ChatCardListState(chattile: chattile);



This code doesn't introduce the tambah constructor, but instead updates the chattile list immediately in the _onSocketInfo_newMessage method. That method still needs to be called from somewhere.

tambah

chattile

_onSocketInfo_newMessage

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