Java.Lang.Classnotfoundexception on Working App

How do I resolve ClassNotFoundException?

Your classpath is broken (which is a very common problem in the Java world).

Depending on how you start your application, you need to revise the argument to -cp, your Class-Path entry in MANIFEST.MF or your disk layout.

How to resolve java.lang.ClassNotFoundException in android?

In the view XML file you are using SquareImageView as the class reference without the full package name. Because you don't include the full package name, Anroid assumes that SquareImageView is in the android.view package and cannot find the class. You need to add the full package name in your view XML file.

java.lang.ClassNotFoundException on my android app but I have no idea why

Try this.

<activity android:label="@string/app_name" android:name=".HelloAndEngine">

You don't need the fully qualified class name. Also, if you are working with Eclipse and rename a package go to Project → Clean and let it clean up your project, fixing up references and so on if anything is broken.

java.lang.ClassNotFoundException for my app

It's possible their device is fubar'd, but I also just noticed your project is setup for JDK builds instead of ADT. You'll want to make sure everything is set up using Properties -> Android instead of Properties -> Java Build, as explained here.

Managing Projects from Eclipse with ADT | Android Developers

It appears others are also having similar issues after upgrading to ADT version 22, so there may be a bug in the SDK. I just checked to see what version I have and found an update to Ver. 22.2.1 available.

Libraries do not get added to APK after update to ADK 22

Error java.lang.ClassNotFoundException stopping me from running the app

I figured it out. The code itself is correct, but the issue was, that I created this project in an old directory with JRE System Library [JavaSE-1.8]. After creating a completely new directory, now with JRE System Library [JavaSE-12] and again with the option "Build Automatically", I copied exactly the same .java file there and now it works fine!

Lesson learned. I hope this would be of any help to somebody.