ClassNotFoundException: Didn't find class "com.google.android.gms.ads.AdView"

Question

I did a lot of research and this seems to be a common error for many users but for very different reasons. None of which I found worked for me.

I'm getting

java.lang.RuntimeException: Unable to start activity ComponentInfo{
[...]/[...].activities.StartActivity}: android.view.InflateException:
Binary XML file line #173: Error inflating class [...].BannerAd
    [...]
Caused by: android.view.InflateException: Binary XML file line #8: Error
inflating class com.google.android.gms.ads.AdView
    [...]
Caused by: java.lang.ClassNotFoundException: Didn't find class
"com.google.android.gms.ads.AdView" on path: DexPathList[[zip file
"/data/app/[...]-1.apk"],nativeLibraryDirectories=[/data/app-lib/[...]-1,
/vendor/lib, /system/lib]]

I'm having the newest versions of ADT and SDK packages installed. I copied google-play-services_lib to my workspace and imported it as a Android project. I added it as a library to my app project. I checked everything under "Order and Export".

I'm having a banner_ad.xml:

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal|top"
    android:orientation="vertical" >

    <com.google.android.gms.ads.AdView
        xmlns:ads="http://schemas.android.com/apk/res-auto"
        android:id="@+id/adView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        ads:adSize="BANNER"
        ads:adUnitId="[...]" />

</LinearLayout>

And a BannerAd.java which I am using:

package [...];

import android.content.Context;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.widget.LinearLayout;

import [...].R;
import [...].general.Settings;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;


public class BannerAd extends LinearLayout {
    public BannerAd(Context context, AttributeSet attrs) {
        super(context, attrs);

        if (!Settings.PRO) {
            LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            mInflater.inflate(R.layout.banner_ad, this, true);

            AdView adView = (AdView) this.findViewById(R.id.adView);
            AdRequest adRequest = new AdRequest.Builder().build();
            adView.loadAd(adRequest);
        }
    }
}

Could it have something to do with proguard? I have no idea, this is my proguard-project.txt file, however:

# To enable ProGuard in your project, edit project.properties
# to define the proguard.config property as described in that file.
#
# Add project specific ProGuard rules here.
# By default, the flags in this file are appended to flags specified
# in ${sdk.dir}/tools/proguard/proguard-android.txt
# You can edit the include path and order by changing the ProGuard
# include property in project.properties.
#
# For more details, see
#   http://developer.android.com/guide/developing/tools/proguard.html

# Add any project specific keep options here:

# If your project uses WebView with JS, uncomment the following
# and specify the fully qualified class name to the JavaScript interface
# class:
#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
#   public *;
#}

-keep class * extends java.util.ListResourceBundle {
    protected Object[][] getContents();
}

-keep public class com.google.android.gms.common.internal.safeparcel.SafeParcelable {
    public static final *** NULL;
}

-keepnames @com.google.android.gms.common.annotation.KeepName class *
-keepclassmembernames class * {
    @com.google.android.gms.common.annotation.KeepName *;
}

-keepnames class * implements android.os.Parcelable {
    public static final ** CREATOR;
}

Any ideas what I could try to fix this?

Edit: Sometimes, I also get such output in the console (but not every time I compile, only sometimes):

[2014-07-24 12:49:05 - [...]] Dx 
trouble processing:
[2014-07-24 12:49:05 - [...]] Dx bad class file magic (cafebabe) or version (0033.0000)
...while parsing com/google/android/gms/internal/mb.class
...while processing com/google/android/gms/internal/mb.class
[2014-07-24 12:49:05 - [...]] Dx 
trouble processing:
[2014-07-24 12:49:05 - [...]] Dx bad class file magic (cafebabe) or version (0033.0000)
...while parsing com/google/android/gms/internal/mc.class
...while processing com/google/android/gms/internal/mc.class
[2014-07-24 12:49:05 - [...]] Dx 
[...]
[Lots of similar warnings here]
[...]
trouble processing:
[2014-07-24 12:49:25 - [...]] Dx bad class file magic (cafebabe) or version (0033.0000)
...while parsing com/google/ads/mediation/customevent/CustomEventAdapter$a.class
...while processing com/google/ads/mediation/customevent/CustomEventAdapter$a.class
[2014-07-24 12:49:25 - [...]] Dx 
trouble processing:
[2014-07-24 12:49:25 - [...]] Dx bad class file magic (cafebabe) or version (0033.0000)
...while parsing com/google/ads/mediation/customevent/CustomEventServerParameters.class
...while processing com/google/ads/mediation/customevent/CustomEventServerParameters.class
[2014-07-24 12:49:25 - [...]] Dx 2786 warnings

Answer 1

This because ProGuard. To safely use ProGuard with Google Mobile Ads, add the following to your ProGuard config:

-keep public class com.google.android.gms.ads.** {
   public *;
}

-keep public class com.google.ads.** {
   public *;
}

Answer 2

I did what @user1684030 said (upgraded Android SDK Build Tools; changed compiler to 1.7), but not worked for me. I've written the solution that I found in case it could help anyone with the same problem:

In the step 3 of Setting Up Google Play Services says:

In your app project, reference Google Play services library project. See Referencing a Library Project for Eclipse for more information on how to do this.

Note: You should be referencing a copy of the library that you copied to your development workspace—you should not reference the library directly from the Android SDK directory.

Solution: Don't do the copy manually. Instead just check the box in Eclipse that says "Copy projects into workspace"

I did it so and everything worked again.

Thanks to this StackOverFlow question: How to fix Google Play Services 2 Library install to Eclipse (Admob is part of Google Play Services)

Answer 3

I finally solved my problems by

• installing the newest version of Android SDK Build Tools (didn't realize that I did not have them yet)
• switching from Compiler compliance level 1.6 to 1.7 (Window - Preferences - Java - Compiler - Compiler compliance level)

Thanks at everybody.