Android binding build error: persistent expression required

Question

I am writing an Android application using DataBinding, referring to https://developer.android.com/topic/libraries/data-binding/index.html .

But when creating my project, it shows an error in the generated class as

> '/databinding/DataBinderMapper.java:10: error: constant expression
> required.'

This error occurs in the switch statement inside the generated DataBinderMapper.java class (this file is an automatically generated file for data binding)

Does anyone know the cause of this error in a java switch event in an automatically generated buld file?

edits: I found the cause of this problem, the link to the layout created in the R.java file is not final for this case. For example, in my case, a layout link in R.java

public static int activity_main=0x7f04001c;

In fact, it should be

public static final int activity_main=0x7f04001b;

But I do not know why this happened and how to change it to final.

Answer 1

This error occurs when your project has a dependency on a library or external plugin separate from the application. The reason for this problem is that the generated identifiers may collide if you have a dependency on multiple libraries / plugins.

Answer 2

It is likely that your model you are communicating with has final modifiers in its variables.