UML Activity Diagram for android project

Question

I have created the below diagram and I wanted to know if the diagram that I have done is correct.

The below diagram is based on an android application. When the application loads the user is given 3 button to select add, update and help. On click on add button the user is given an option to add a new user or add a new item. When he select either of the options he enters the required data once the data is entered the system check if all the values are entered correctly and then finally saved. The same process is applied for update.

Answer 1

Your diagram misses an entry point. Though it's rather obvious that the top action is the start, only the entry point is the one indicating the beginning.

You can omit most of the diamonds and directly transfer via a guard from actions. So your conditions should be guards and written as [Yes] or [No]. The top most action (and quite some others) is(/are) indeed what should be written inside (or aside) the diamond below.

An excerpt for an update could look like this:

Finally Values added does not look like an action but rather as state. It should be omitted. Alternatively use differently named end flows.

So far for the formal points. But as @eyp said: it's a good one and one can understand what you tried to express. The above is just for the picky teachers.