dart - 为什么 FocusNode 需要在 flutter 中配置？

Question

什么时候在 flutter 中使用 dispose 我有点困惑。有没有关于这个的好教程？

在食谱中 https://flutter.io/docs/cookbook/forms/focus :

void dispose() {
  // Clean up the focus node when the Form is disposed
  myFocusNode.dispose();

  super.dispose();
}

为什么我必须调用 myFocusNode.dispose();？如果我不打电话会发生什么？

请解释清楚，或者给我一些明显的错误代码示例，在不为 FocusNode 或其他情况调用 dispose 时显示错误结果，而不是简单地告诉我这会导致内存泄漏...

非常感谢。

Answer 1

As from the documentation:

Focus nodes are long-lived objects. For example, if a stateful widget has a focusable child widget, it should create a FocusNode in the State.initState method, and dispose it in the State.dispose method, providing the same FocusNode to the focusable child each time the State.build method is run. In particular, creating a FocusNode each time State.build is invoked will cause the focus to be lost each time the widget is built.

换句话说，处理它们可确保每次构建小部件时节点正确调用焦点，其他调用焦点的小部件没有问题，并且还保留了性能。