flutter父组件如何调用子组件？

Question

How does the parent component trigger the methods of the child component? How do I trigger the click method of son in fathor? As shown below:

Answer 1

As mentioned, you need to use a callback. What this means it that you pass a function to your child that it calls when it needs to. You'll be working from the inside up, not top down.

You'll store the function as a member variable and when your child is clicked you'll call that function. The function will be called in your parent, you can pass whatever data you want back to the parent just like calling a normal function.

Here's some pseudo-code you can use to make the adjustment

class son extends StatelessWidget {
  Function onClicked;

  son({this.onClicked});

  Widget build(...) {
    return GestureDetector(
      child: Container(...),
      onTap: onClicked
    )
  }
}

class father extends StatelessWidget {
  Widget build(...) {
    return Container(
      child:son(onClicked: _clicked)
    )
  }

  void _clicked() {
    print('clicked');
  }
}

Also, Definitely change your class names to start with a Capital letter.

Answer 2

class Father extends StatelessWidget {
  var child;

  @override
  Widget build(BuildContext context) {
    child = son();
    
    return Scaffold(
      body: child,
      floatingActionButton: FloatingActionButton(
        onPressed: () => child?.childFunction(),
      ),
    );
  }
}

class Son extends StatelessWidget {
  void childFunction() => print('called in child widget');

  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.red,
    );
  }
}