Thread, handler and activity structure for a bouncing ball animation
I don't have time to do a full review, but here are some pointers.


Don't use raw access to members (view.x), but always use getters/setters instead.  It has been a Java convention for about 15 years.  Also, you should declare all your members as private.
Don't do many assignements on a single line (int x = view.x,y = view.y, ...).  Again, it does work, but the Java convention is to have one assignment per line.
Don't have Ball being a member of MyActivity and MyActivity being a member of Ball.  That is spaghetti code.
Avoid using Thread in Android, or Java.  There are cleaner and less dangerous patterns for working with concurrent code. For Android, you should look into AsyncTask; for example this.  You can probably find a more appropriate pattern if you look harder.
I haven't touch Android for a while, but I don't think onWindowFocusChanged is the usual callback where everything is started.