Android数据绑定：无法解析符号

Question

I have tried to use the beta features(data binding) in the android studio. After following the guides from the android studio, I can find the related class DataBindingInfo in the android studio. But the databinding class does not generate after I create the project. Can someone help?

build.gradle for the app module

apply plugin: 'com.android.application'

apply plugin: 'com.android.databinding'
android {
    compileSdkVersion 23
    buildToolsVersion "23.0.1"

    defaultConfig {
        applicationId "com.example.pigfamily.myapplication"
        minSdkVersion 15
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:23.0.1'
}

build.gradle for the project

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        dependencies {
            classpath "com.android.tools.build:gradle:1.3.0"
            classpath "com.android.databinding:dataBinder:1.0-rc1"
        }
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>

        <variable
            name="user"
            type="com.example.pigfamily.myapplication.User" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
 >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{user.name}" />

    </LinearLayout>
</layout>

MainActivity.java

package com.example.pigfamily.myapplication;

import android.databinding.DataBindingUtil;
import android.databinding.ViewDataBinding;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ActivityMainBinding //cannot resolve the symbol here
    }

    @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_main, 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);
    }
}

Answer 1

enable dataBinding in your App Level build.gradle file

android {
    ...
    dataBinding{
        enabled=true
    }
}

Answer 2

I had this same problem. I was digging through gradle settings, cleaning, rebuilding... nothing worked. Finally all I had to do was restart Android Studio

https://www.bignerdranch.com/blog/descent-into-databinding/

As of this writing, this integration needs a little jump-start to get going. To make ListItemCrimeBinding available after adding the tag, you must restart Android Studio, then rebuild the project.

Answer 3

to implement binding, make sure that:

1. in the app.gradle , enable dataBinding :

    apply plugin: 'com.android.application' ... android { ... dataBinding { enabled = true } ... } dependencies { ... }

2. wrap the existing XML layout in a <layout> element:

    <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"> <!-- note: xmlns above only needed if used in original XML --> <!-- original XML here --> </layout>

3. in Activity / Fragment , use the Binding

    val binding = XmlLayoutNameBinding.inflate(context.layoutInflater) // use the layout

4. if is unable to resolve the XxxBinding class (even though it can resolve XxxBindingImpl )

   1. first try changing a character in ANY XML layout with the tag
   2. if that doesn't work, restart Android Studio , sync & rebuild project

Answer 4

Add on build.gradle(:app) viewBinding true

android {
  buildFeatures {
        viewBinding true
    }

}

Answer 5

如果弹出对话框，请单击同步，单击保存旁边的同步按钮，或重新启动 Android Studio。

Answer 6

If clear Project and Rebuild Project don't work for you try the simple solution. It sometimes doesn't work when you clone a project from remote git branches .You need to just close your project and delete the .gradle and .idea folder of your android project. Then reopen the project.

Answer 7

For me I had to add:

buildFeatures {
    viewBinding true
}

to my build.gradle file, then run File->Sync Project With Gradle Files

Answer 8

In my case, my layout file had some errors and therefore AS was not creating the binding class. I could find it by expecting the XML file and seeing the error messages.

Answer 9

be sure you add data binding in your build.gradle

and after that sync project after that Restart and clear caches from the file in android studio . this way solve my problem

Answer 10

For my case I added :

         dataBinding {
                  enabled=true
         }

Then went to File > Settings > Gradle > Untick offline work> Apply> Ok Then cleaned my project.

Answer 11

I've seen this answer nowhere so I suggest: if you added some activity from context menu by clicking on some package like 'data' or 'ui', Android Studio saved path to binding like so: import com.damian.yourappname.ui.databinding.ActivitySearchBinding;

I tested it a few times with my previous projects and it occurs only when sample activity like ScrollingActivity is added to a package other package for all classes. import com.damian.yourappname.databinding.ActivitySearchBinding;

So best way is just creating sample activity in root folder and after gradle sync moving to some package

Answer 12

I found a way without restart or invalidate cache. I thing this because binding need to restart or something, so I re-write private ActivityMainBinding binding; and viewBinding work again.

I don't know why this work but this save my time than restart/invalidate cache

Answer 13

In my case i deleted build, build-cache folders in project scope, then build folder in app module. Afterwards restarted PC and it started working

Answer 14

1.Add Below in app gradle

 dataBinding {
        enabled = true
    }

2.In xml layout write below code

<layout
    xmlns:android="http://schemas.android.com/apk/res/android">
  <data></data>
</layout>

UPDATED: CLEAN AND REBUILD THE PROJECT