Applicationid Cannot Be Null

I am trying to run this simple sample log in test, but I always get the same problem: 'applicationId ' cannot be null. I have read questions from before, but no one solve my proble

Solution 1:

 <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/app_id"/>

should be inside the application tag

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.facebooksharetest"
    android:versionCode="1"
    android:versionName="1.0">

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">
        <activity
            android:name="com.example.facebooksharetest.MainActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <meta-data
            android:name="com.facebook.sdk.ApplicationId"
            android:value="@string/app_id" />
    </application>
</manifest>