Again, these are callbacks to the View class, so your only chance to define them is when you build a custom component.

再说一次，这些是View类相关的回调方法，所以你只能在你构建自定义组件时定义它们。

youdao

The View class serves as the base for subclasses called "widgets," which offer fully implemented UI objects, like text fields and buttons.

View类是它称为“widgets（工具）”的子类的基础，它们提供了诸如文本输入框和按钮之类的UI对象的完整实现。

youdao

This is what you should do when you've implemented your own View class and want to listen for specific events that occur within it.

这种方法主要用于你自己实现了一个View类，并想侦听其上发生的特定事件。

youdao

The welfare state's expansion into every nook and cranny of too many people's lives has been less about saving people from deprivation and expresses more a condescending middle-class view of people as helpless and hapless unless the state helps them to parent correctly, improve their lifestyles, cut down on smoking or drinking, etc.

BBC: UK

In her view, it is middle-class Roma who are leaving in frustration.

ECONOMIST: The Roma in eastern Europe: Canada home and dry | The

With its stunning Renaissance art and architecture on view in well-proportioned squares and in world-class museums, there is a sense of elegance and permanence that helps root all who live here.

BBC: Living in: Florence