An internal error occurred during: "Launching Project". java.lang.NullPointerException

Question

My android project was compiling well but suddenly it stopped launching. Then I tried to launch other projects from Project Explorer and all project threw same exception:

An internal error occurred during: "Launching Project". java.lang.NullPointerException

But console always shows everything is normal.

Android Launch!
adb is running normally.
Performing com.mmcolrev.LoginActivity activity launch

Here's screenshot of error.

Answer 1

If anyone face this problem, first keep in mind that error is not in your code but due to some internal issue in eclipse ADT. I don't know exact problem but luckily found way to solve it. If you ever encounter this error follow steps below:

1. Exit Eclipse.
2. Go to Android workspace.
3. Locate .metadata folder(make sure you set hidden folder visibility on).
4. Delete .metedata folder.
5. Start Eclipse(you will notice project explorer is empty, don't panic) and import all your projects.

Answer 2

Removing Gen/R.java and restarting eclipse, worked for me.