android data binding error cannot find symbol class

Question

I am getting started for using DataBinding feature  I am facing problem with it      Error  21  9  error  cannot find symbol class   ContactListActivityBinding   build gradle Module  app   apply plugin   com android application   android       compileSdkVersion 23     buildToolsVersion  23 0 2       defaultConfig           applicationId  com letsnurture ln 202 databindingdemo          minSdkVersion 15         targetSdkVersion 23         versionCode 1         versionName  1 0            buildTypes           release               minifyEnabled false             proguardFiles getDefaultProguardFile  proguard-android txt     proguard-rules pro                      dataBinding           enabled   true          dependencies       compile fileTree dir   libs   include      jar        testCompile  junit junit 4 12      compile  com android support appcompat-v7 23 1 1      compile  com android support design 23 1 1      ContactListActivity java  import android databinding DataBindingUtil  import android os Bundle  import android support design widget FloatingActionButton  import android support design widget Snackbar  import android support v7 app AppCompatActivity  import android support v7 widget Toolbar  import android view View  import android view Menu  import android view MenuItem   import com letsnurture ln 202 databindingdemo model Contact   public class ContactListActivity extends AppCompatActivity         Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState            ContactListActivityBinding binding   DataBindingUtil setContentView this  R layout activity contact list           Contact user   new Contact  Chintan Soni     91 9876543210            binding setContact user              setContentView R layout activity contact list           Toolbar toolbar    Toolbar  findViewById R id toolbar           setSupportActionBar toolbar            FloatingActionButton fab    FloatingActionButton  findViewById R id fab           fab setOnClickListener new View OnClickListener                  Override             public void onClick View view                    Snackbar make view   Replace with your own action   Snackbar LENGTH LONG                           setAction  Action   null  show                                          Override     public boolean onCreateOptionsMenu Menu menu               Inflate the menu  this adds items to the action bar if it is present          getMenuInflater   inflate R menu menu contact list  menu           return true              Override     public boolean onOptionsItemSelected MenuItem item               Handle action bar item clicks here  The action bar will            automatically handle clicks on the Home Up button  so long            as you specify a parent activity in AndroidManifest xml          int id   item getItemId               noinspection SimplifiableIfStatement         if  id    R id action settings                return true                     return super onOptionsItemSelected item             content contact list xml   lt  xml version  1 0  encoding  utf-8   gt   lt layout xmlns android  http   schemas android com apk res android      xmlns app  http   schemas android com apk res-auto      xmlns tools  http   schemas android com tools      tools context  com letsnurture ln 202 databindingdemo ContactListActivity      tools showIn   layout activity contact list  gt        lt data gt            lt variable             name  user              type  com letsnurture ln 202 databindingdemo model Contact    gt       lt  data gt        lt LinearLayout         android layout width  match parent          android layout height  match parent          android orientation  vertical          android padding   dimen activity horizontal margin          app layout behavior   string appbar scrolling view behavior  gt            lt TextView             android layout width  wrap content              android layout height  wrap content              android text    user contactName               tools text  Name    gt            lt TextView             android layout width  wrap content              android layout height  wrap content              android text    user contactNumber               tools text  Number    gt       lt  LinearLayout gt   lt  layout gt    activity contact list xml   lt  xml version  1 0  encoding  utf-8   gt   lt android support design widget CoordinatorLayout xmlns android  http   schemas android com apk res android      xmlns app  http   schemas android com apk res-auto      xmlns tools  http   schemas android com tools      android layout width  match parent      android layout height  match parent      android fitsSystemWindows  true      tools context  com letsnurture ln 202 databindingdemo ContactListActivity  gt        lt android support design widget AppBarLayout         android layout width  match parent          android layout height  wrap content          android theme   style AppTheme AppBarOverlay  gt            lt android support v7 widget Toolbar             android id    id toolbar              android layout width  match parent              android layout height   attr actionBarSize              android background   attr colorPrimary              app popupTheme   style AppTheme PopupOverlay    gt        lt  android support design widget AppBarLayout gt        lt include layout   layout content contact list    gt        lt android support design widget FloatingActionButton         android id    id fab          android layout width  wrap content          android layout height  wrap content          android layout gravity  bottom end          android layout margin   dimen fab margin          android src   android drawable ic dialog email    gt    lt  android support design widget CoordinatorLayout gt

User · Answer

Don t forget to add in app level gradle  apply plugin   kotlin-kapt

User · Answer

Make sure the name for your model and the reference have the same name   For example  name  item  must match android checked     item checked     lt data gt       lt variable         name  item          type  com simone mywordlist model MyModel    gt   lt  data gt                lt Switch                 android id    id my switch                  android layout width  wrap content                  android layout height  wrap content                  android checked     item checked                 gt

User · Answer

I have got the same error  but with Kotlin usage   To resolve it  i make some changes in gradles files    In project s Gradle file     dependencies       classpath  com android tools build gradle 3 1 2      classpath  org jetbrains kotlin kotlin-gradle-plugin 1 2 40      In app s Gradle file    dependencies                implementation  android arch lifecycle extensions 1 1 1      compile  org jetbrains kotlin kotlin-stdlib-jdk7 1 2 30      kapt  com android databinding compiler 3 1 2      kapt       generateStubs   true      used to resolve annotation conflicts configurations all       resolutionStrategy           force  com android support support-annotations 23 1 1

User · Answer

You must change your activity contact list to be binded - add layout tag as you did in content contact list  Don t forget  The root layout inside activity contact list must have an id for the Binding class to be generated and will be named ActivityContactListBinding  i e  the name of the layout with camel casting instead of underscores    Next  inside activity contact list  give  lt include layout   layout content contact list    gt  an id  then you will have access for its binding instance through your ActivityContactListBinding instance   Somthing like   binding contentContactList setContact user     Let me know if it works

User · Answer

Keypoint Your layout name is in snake case  activity login xml  Then your binding class name will be in CamelCase  ActivityLoginBinding java  Also build project after creating layout  Sometimes it is not generated automatically

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This problem may be occur when there is problem in layout file   In my case I just use wrong way to call method  android onClick        - gt  viewModel showText       instead of    android onClick       - gt  viewModel showText

User · Answer

For me it was an error in the layout xml binding  I had   app setNameString    person    instead of  app nameString    person    the type name must match the name you have set up in the  BindingAdapter class  if you are using binding adapter

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After ensuring the naming conventions are correct as described in other answers  and also trying to invalidate the cache and restart  deleting temp cache folders the issue still persisted for me  I got rid of it as follows  Add a new dummy XML resource  This will trigger bindings and its meta-data to re-create across the project  The annoying compile errors should no longer be visible anymore  You now delete the dummy XML you added  For me as of August 2020  the Binding would automatically get corrupted repeatedly  It seems to be biting more than it can chew under the hood

User · Answer

In my case  there was a package with the same name as a missing import in the generated databinding class   It seems like the compiler got confused

User · Answer

Please refer to the android developer guide     Layout file was main activity xml so the generate class was MainActivityBinding   Since your xml is named  activity contact list xml   you should use ActivityContactListBinding instead of the original one

User · Answer

I consistently run into this problem  I believe it has to do with android studio not being aware of dynamically generated files  If you have everything else right for databinding try to File   Invalidate Caches Restart     and select Invalidate Caches and Restart  Then try and import the BR file    it should import fine   You may have to throw in a Clean and Rebuild

User · Answer

Actually it can be happend for various reason and for poor logging mechanism in data binding it is very hard to find the reason So go got the proper error first go to the terminal and run the following command- gradlew  app build --stacktrace  It will show you the proper error with the number of line in XML where error is found  For example - ERROR  Could not find accessor com example model file   app src main res layout fragment example xml Line 91

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You can see Main Answer for complete information about data binding errors and solutions  I will try to tell some important points below  5 Tips that I use to solve binding issues  Assuming that you have enabled data binding in build gradle and you have converted your layout to binding layout  First of all binding class auto generate when you convert layout to binding layout  Still sometimes it is not generated when background threads are not working  Here are some tips for you to resolve this    1  Name of generated class  Layout name is in snake case activity main xml Data binding class will be in PascalCase like ActivityMainBinding    2   Type full name of Binding class  I felt sometimes when you type ActivityMai     then it does not show suggestion  but that does not mean class is not generated  In that case you should type full name of expected generated class  Like type ActivityMainBinding and it will show import popup   That s what i faced many times   Still not getting import suggestion  Try manual import  import  lt yourpackage gt databinding ActivityMainBinding     3   Rebuild Project  If still your class is not generated   Some time when we paste layout file  then it happens   Then Rebuild Project from Build gt  Rebuild  Not Build or Make project   It will generate your data binding class   Rebuild does Magic for me all times    4  If you have created an  lt variable in your layout and it does not show up its setter and getter in data binding class  then follow 4th point   5  Still if your class is not generating then you should check if build is not failing due to an error in your layout file  Data binding class will generate with a successful build  This is all what i do to solve my data binding errors  If you get any further issue  you can comment here  Source answer

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Just remove  build  folder in youy project directory and compile again  i hope it works for you too

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Improper package names can also cause the above error  As of Android Gradle plugin 3 2  as far as I can tell  CamelCase package names will be inferred improperly as classes  which will break the generated binding object   Example   src   - gt  FooPackage           - gt  Bar java   will be generated wrongly as  import src FooPackage       public abstract class MyBinding extends ViewDataBinding        NonNull     public final FooPackage Bar mInstance          This obviously doesn t make any sense   Refactor FooPackage to foopackage according to java conventions and be saved  You will then get   import src foopackage Bar       public abstract class MyBinding extends ViewDataBinding        NonNull     public final Bar mInstance

User · Answer

I have got the same issue and I found that variable name and method were missing  Double check the layout file or look for build error that says DATABINDINGISSUE  or invalidate and restart android studio  It should work

User · Answer

You need to add the  tags into your Activity s Xml Layout    lt  xml version  1 0  encoding  utf-8   gt   lt layout xmlns android  http   schemas android com apk res android          xmlns app  http   schemas android com apk res-auto          xmlns tools  http   schemas android com tools  gt       lt data gt           lt variable              name                 type      gt       lt  data      lt android support design widget CoordinatorLayout          android layout width  match parent          android layout height  match parent          android fitsSystemWindows  true    tools context  com letsnurture ln 202 databindingdemo ContactListActivity  gt        lt  android support design widget CoordinatorLayout gt   lt  layout gt    and then  add an android id into your  tag  After that  you ll have a ActivityContactListBinding object and you can access and bind variables on your included layouts

User · Answer

make all your packages name s in the project that you used in binding to lower case

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Your problem might actually be on this line   lt include layout  quot  layout content contact list quot    gt   Android Studio gets a little confused at time and takes the include layout for the layout tag  What s even more frustrating is that this could work the first time  fails to work with a modification on the Java Kotlin code later  and then work again after a tweak that forces it to rebuild the binding  You may want to replace  lt include gt  tags with something that populates it dynamically

User · Answer

Sometimes the reason of these errors are not the DataBinding itself  but some other part of our code  In my case I had an error in Room database so the compiler couldn t generate the binding classes and it gives me these errors   According to Google      Previous versions of the data binding compiler generated the binding classes in the same step that compiles your managed code  If your managed code fails to compile  you might get multiple errors reporting that the binding classes aren t found  The new data binding compiler prevents these errors by generating the binding classes before the managed compiler builds your app    So to enable new data binding compiler  add the following option to your gradle properties file   android databinding enableV2 true   You can also enable the new compiler in your gradle command by adding the following parameter   -Pandroid databinding enableV2 true   Note that the new compiler in Android Studio version 3 2 is enabled by default

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You need to declare and pass the binding in the activity layout  not in the included layout   Example from the documentation    lt  xml version  1 0  encoding  utf-8   gt   lt layout xmlns android  http   schemas android com apk res android      xmlns bind  http   schemas android com apk res-auto  gt      lt data gt          lt variable name  user  type  com example User   gt      lt  data gt      lt LinearLayout        android orientation  vertical         android layout width  match parent         android layout height  match parent  gt          lt include layout   layout name             bind user    user    gt          lt include layout   layout contact             bind user    user    gt     lt  LinearLayout gt   lt  layout gt       Here  there must be a user variable in both the name xml and contact xml layout files

User · Answer

your model just have getter and setter in androidX  else not find your model in view and show this bug  public class User    String name   public String getName         return name    public User String name        this name   name

User · Answer

I fell into this issue because my Activity was called MainActivityMVVM and the Binding was converted into MainActivityMvvmBinding instead of MainActivityMVVMBinding  After digging into the generated classes I found the issue

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this is your code  ContactListActivityBinding binding   DataBindingUtil setContentView this  R layout activity contact list     Replace this code  ActivityMainBinding binding   DataBindingUtil setContentView this  R layout activity contact list

User · Answer

In my case I had the same issue but the reason was different  My onClick function was declared private in the activity class  so be sure that  if you are using a handler function inside the layout  the function must not be private      this will not be visible in the binded layout because it s private  private fun mainButtonClick view  View        if  viewModel isRecording value    true            stopRecordingAndPlaying         else           startRecordingAndPlaying

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In my project it was a trouble in   android text    safeUnbox viewmodel population      So I ve wrapped it in String valueOf      android text    String valueOf safeUnbox viewmodel population       And it was resolved

User · Answer

I was calling my onClick wrong  which caused this error  So I changed  android onClick    listener onDogClicked       to   android onClick    listener  onDogClicked

[android] android: data binding error: cannot find symbol class

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