Data-Binding fails with "couldn't make a guess"

Question

Since the update to Android Studio 3.2.0 I face the following issue:

Execution failed for task ':mobile:dataBindingGenBaseClassesDebug'.

> couldn't make a guess for com.ACME.database.model.Order

also seen this answer, which hints for that "package-names must start with a lower-case letter".

... it seems alike, as if this variable assignment would be the cause:

<data class=".databinding.OrderFragmentBinding">
    <variable name="order" type="com.ACME.database.model.Order"/>
    ...
</data>

found: New data binding compiler for binding classes, which does not explain the change in behavior.

Q: are such assignments also affected by that naming convention? I mean, is there any chance (beside changing the uppercase package-name) to make that data-binding v2 "guess" work out?

Answer 1

these settings in the gradle.properties do enable the androidx data-binding compiler:

android.databinding.enableV2 = false
android.enableExperimentalFeatureDatabinding = true

one can see that by the fetched package:

Download https://dl.google.com/dl/android/maven2/androidx/databinding/databinding-compiler/3.2.0/databinding-compiler-3.2.0.pom
Download https://dl.google.com/dl/android/maven2/androidx/databinding/databinding-compiler/3.2.0/databinding-compiler-3.2.0.jar

and it complains:

WARNING: The option setting 'android.databinding.enableV2=false' is experimental and unsupported.
The current default is 'true'

WARNING: The option setting 'android.enableExperimentalFeatureDatabinding=true' is experimental and unsupported.
The current default is 'false'

most likely androidx.fragment.app.Fragment instead of android.support.v4.app.Fragment would be required, in order to data-bind a Fragment with the default v2 data-binding compiler. this is also just a temporary solution - but still better than to revert to the v1 data-binding compiler.

---

Update:

Since com.android.tools.build:gradle:3.5.0 the above workaround does not work anymore; One has to refactor the XML files. It works best when not adding any class="" attribute into the <data /> tag - and also adding this tag into any existing <layout> tag. Duplicate id on data-bound <include> tags may also prevent the generation (the id has to be set on the <include> tag, not in the included layout).

Answer 2

Same thing happening to me after updating to 3.2 (working application before the migration, and no code change)... then this "guess" issue even though I do have lowercase in the first letters of the package name!

<data>
   ...
   <variable name="rule" type="com.gta.viewmodels.vmRule"/>
   ...
</data>

So I "guess" your issue will still remain even after you update the package name (which is best practice anyways, given issues appear every single time I upgrade Android Studio!).

Anyway, I solved by downgrading the v2 databinding in gradle.properties (you'll get an "unsupported" warning, but just ignore it):

android.databinding.enableV2=false

Looks like the Android Studio PG hasn't tested that well this assertion (here):

Data Binding V2 is now enabled by default and is compatible with V1.

Answer 3

Had a similar problem. Solved by renaming the data class by starting with capital letters.

Answer 4

Its because of your class name or package name which use databinding. These classes( which use databinding) has to started with capital letter and packages started with lowercase.

Answer 5

I have faced this issue because 1.my viewmodel classes was not extended from BaseObservable

2. my package name starts with capital letter

Answer 6

I got this error and it solved by changing the first letter of clickhandler class name to the capital I changed this: clickHandler to this: ClickHandler com.packagename.android.activity.AddAddressActivity.ClickHandler

Answer 7

A case where you will run into this error:

<data>
    <variable
        name="something"
        type=""/>
</data>

Empty type or undefined Type

Answer 8

Just in case nothing of the above works, check if the class type your referencing is in the same module or in a module on which the module where the xml is dependes.

Answer 9

In my case it was just a incorrect path in the type variable XML file

<data>
        <variable
            name="clickListener"
            type="com.example.liberdade.caixa.CaixaListener" />

Answer 10

I my case I was using class name in small alphabets (propertyModel) should be (PropertyModel)

Answer 11

If your package start capital letter change it to small it will fix the problem.

Answer 12

rename your package to have all small letters, after changing my package from

"com.AmoTech.unischool" to "com.amotech.unischool"

, the errors disappeared and i was able to build without errors in android studio. image showing change of package

Answer 13

All the directories must be in simple letters , otherwise this error arises

example

package com.saw1993.mrep.activities.products