Error:
XML verification failed for https://dlssl.google.com/android/repository/repository.xml.
Error: java.lang.NullPointerException
Solution:
This error occurs on Mac because, Java 6 is not installed by default on osX 10.5.6 or before and you need Java 6 to run Android AVD and SDK Manager.
The easiest way to overcome this error is by installing the latest version of Java.
To install, do the following:
Go to Apple Menu ---> Software Update ---> Tick the checkbox of Java Software Update ---> Click Install
I found this as the easiest way to update Java. I tried to download newer version of Java but later realized that I have wasted 10 minutes in searching for a direct download.
After the installation, now run the Android AVD and SDK Manager and try installing the packages. If you are still getting some error, do the following:
Go to Applications ---> Utilities ---> Run Java Preferences (In some machines, Java Preferences application might be present in Java Folder).
In the General Tab, change the order of Java versions in both the Java Applet box and Java Applications box by moving the Java SE 6 to the top in the order of Java Versions.
After the above steps, Android SDK and AVD Manager should run smoothly.
Happy Programming 
Viplav
