Why should alertdialog be created using an internal static class builder in Android?

I recently read some AndroidCodeIt is found that his alertdialog needs to be created using code similar to the following:

New alertdialog. Builder (this) <br/>. xxxx

Go to the alertdialogSource codeYou can see that alertdialog is inherited from dialog, and its constructor is declared as protected. Builder is an internal public static class. most of the Methods of builder are to set an alertcontroller. alertparams object. only when the builder is called. when creating or show (in fact, show also calls create first), it will actually create an alertdialog object, and set some parameters of alertparams to this alertdialog object.

 

But I never figured out what special effects or benefits it would bring. Just to make the structure look a little clearer? Is there a deep meaning?

 

Conclusion: This is an application of building complex objects in builder mode. In builder. Create or Params settings, You can implement the constraint rules for alertdialog. Alertdialog declares the protected constructor to prevent external code from directly going to the new object without building, resulting in constraints failure.