问题描述

据我所知，有两种方法可以从 Activity 中显示 Dialog.

As far as I can tell, there are two ways to show a Dialog from an Activity.

1. 创建 Dialog(例如，使用 AlertDialog.Builder)，然后调用新创建的 Dialog 的 show() 方法.
2. 调用 Activity 的 showDialog() 方法，传入一个 int，它唯一地定义了您想要构建的 Dialog 类型.然后重写 onCreateDialog() 以实际构建 Dialog，Android 将为您显示它.

1. Create the Dialog (for example, using an AlertDialog.Builder), and then call the newly created Dialog's show() method.
2. Call the Activity's showDialog() method, passing in an int that uniquely defines what sort of Dialog you want to build. Then override onCreateDialog() to actually build the Dialog, and Android will display it for you.

第二种方法似乎是标准做法，但我很好奇我使用哪种方法是否重要.以下是我能想到的:

The second method seems to be the standard practice but I'm curious if there is any reason it matters which one I use. Here's all I can come up with:

使用Dialog.show

1. 如果您需要以某种方式参数化 Dialog，使用 Activity.showDialog 可能会有点尴尬，如 这个问题.您可能必须在成员变量中存储字符串或其他内容，以便稍后在 onCreateDialog 或 onPrepareDialog 期间检索它.
2. 创建和修改对话框的逻辑分布在多个地方，可能会使代码更难阅读和维护:
   • 你调用showDialog()
   的地方
   • 在被覆盖的 onCreateDialog 方法中可能很大的 switch 语句中
   • 在被覆盖的 onPrepareDialog 方法中可能很大的 switch 语句中

1. If you need to parameterize the Dialog in some way, it can be a little awkward to use Activity.showDialog, as described in this question. You may have to store a String or something in a member variable, just so that it can be retrieved moments later during onCreateDialog or onPrepareDialog.
2. The logic for creating and modifying the dialog is spread out across a number of places, potentially making the code harder to read and maintain:
   • The place where you call showDialog()
   • Inside a potentially large switch statement in the overridden onCreateDialog method
   • Inside a potentially large switch statement in the overridden onPrepareDialog method

使用Activity.showDialog的原因:

1. Activity.showDialog 的 API 文档说 Dialog 是由 Activity 管理"的，我想这会带来一些好处吗?但如果你使用 AlertDialog.Builder 也是如此，我认为，因为你将 this 作为参数传递给 Builder 的构造函数.
2. 如果您的 Activity 将多次显示相同(或非常相似)的 Dialog，则此选项只创建一次，而不是每次都创建一个新的，从而减少系统分配空间的压力用于新对象、垃圾回收等.

1. The API docs for Activity.showDialog say that the Dialog is "managed" by the Activity which I suppose provides some benefit? But this is also true if you use the AlertDialog.Builder, I would think, because you pass in this as an argument to the Builder's constructor.
2. If your Activity is going to show the same (or a very similar) Dialog several times, this option creates it only once, instead of creating a new one each time, thus putting less strain on the system as far as allocating space for new objects, garbage collection, etc.

所以我的问题是，决定何时使用Activity.showDialog和何时使用Dialog.show的标准是什么，为什么?

So my question is, what are the criteria for deciding when to use Activity.showDialog and when to use Dialog.show, and why?

推荐答案

在我看来你应该更喜欢 showDialog 因为这个方法会为你完成大部分工作.例如，您不必担心更改屏幕方向后会丢失对对话框的引用.它将自动重新创建.Dialog.show 更容易出错.

In my opinion you should prefer showDialog because this method will do most of the work for you. In example You don't have to worry that you will lose reference to your dialog after changing screen orientation. It will be recreated automatically. Dialog.show is much more prone to errors.

所以我建议你尽可能使用 showDialog.

So I suggest you to use showDialog everywhere you can.

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