How Make Copy List Into Another List In Flutter Android App

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  List<int> intList = [1, 2, 3, 4,];
  var stringList = ['Apple', 'Bananaa', 'Orange','Mango',];
  void copyList() {
    List<int> newList_1 = List.from(intList);
    var newList_2 = List.from(stringList);
    print(newList_1);
    print(newList_2);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
        home: Scaffold(
            body: Center(
                child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Container(
                          margin: const EdgeInsets.fromLTRB(20, 10, 20, 10),
                          child:
                          RaisedButton(
                            onPressed: () => copyList(),
                            child: Text('Copy List Into Another List'),
                            textColor: Colors.white,
                            color: Colors.pink,
                            padding: EdgeInsets.fromLTRB(12, 12, 12, 12),
                          )
                      ),
                    ])
            )
        )
    );
  }
}