android: data binding error: cannot find symbol class
<p>I am getting started for using <code>DataBinding</code> feature. I am facing problem with it.</p>

<blockquote>
  <p>Error:(21, 9) error: cannot find symbol class
  ContactListActivityBinding</p>
</blockquote>

<p><strong>build.gradle(Module: app)</strong></p>

<pre><code>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'
}
</code></pre>

<p><strong>ContactListActivity.java</strong></p>

<pre><code>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);
    }
}
</code></pre>

<p><strong>content_contact_list.xml</strong></p>

<pre><code>&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;
</code></pre>

<p><strong>activity_contact_list.xml</strong></p>

<pre><code>&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;
</code></pre>