Android 惰性数据绑定(bind)可能吗？

Question

Android 数据绑定(bind)支持最酷的功能之一是它还可以为带有 ID 集的 View 生成字段。这整理了代码库，因为不需要字段或 findViewById() 调用。

但问题是绑定(bind)实例只能通过倾向于安排绑定(bind)的 bind() 调用来检索。当异步接收数据并且通常会抛出 NullPointerException 时，这是很糟糕的。

是否可以在不进行实际数据绑定(bind)过程的情况下检索带有 View 字段的绑定(bind)实例？

堆栈跟踪:

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.Boolean.booleanValue()' on a null object reference
         at com.app.android.databinding.ActivityRestaurantDetailsBinding.executeBindings(ActivityRestaurantDetailsBinding.java:381)
         at android.databinding.ViewDataBinding.executePendingBindings(ViewDataBinding.java:350)
         at android.databinding.ViewDataBinding$6.run(ViewDataBinding.java:167)
         at android.databinding.ViewDataBinding$5.onViewAttachedToWindow(ViewDataBinding.java:137)
         at android.view.View.dispatchAttachedToWindow(View.java:14525)

Answer 1

这似乎没有意义，数据绑定(bind)将忽略空变量，因此不应抛出空指针，我认为这是它最受推崇的功能之一。如果您需要在异步调用等之后修改变量，您可以使用 dataBinding.executePendingBindings()

来自 the docs

The generated binding class will have a setter and getter for each of the described variables. The variables will take the default Java values until the setter is called — null for reference types, 0 for int, false for boolean, etc.

和

Generated data binding code automatically checks for nulls and avoid null pointer exceptions. For example, in the expression @{user.name}, if user is null, user.name will be assigned its default value (null). If you were referencing user.age, where age is an int, then it would default to 0.