The parent component of the Flutter calls the child component method

GlobalKey<_SonState> sonKey = GlobalKey();

/ / child component
import 'package:flutter/material.dart';

// The key is the sonKey variable
GlobalKey<_SonState> sonKey = GlobalKey();

class Son extends StatefulWidget {
  Son({Key key}) : super(key: key);

  @override
  _SonState createState() => _SonState();
}

class _SonState extends State<Son> {
// The method to be called by the parent component
  void sonFn() {
    print('call sonFn');
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('Child component')); }}Copy the code

/ / the parent component
import 'package:flutter/material.dart';
// Introduce the son component
import 'son.dart';

class Father extends StatefulWidget {
  Father({Key key}) : super(key: key);

  @override
  _FatherState createState() => _FatherState();
}

class _FatherState extends State<Father> {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        // sonKey is used to define sonKey
        Son(key: sonKey),
        // The trigger button calls the child component method
        RaisedButton(
          onPressed: () {
            // Use the subcomponent method
            sonKey.currentState.sonFn();
          },
          child: Text('Click I call child component method'), a)],); }}Copy the code