Question

“Not all code paths return a value”

 public BallData GetBall(String Name)
    { 
        //Check each item in the list for the name.
        foreach (BallData Item in _BallList)
        {
            //If the name matches, return the item to the caller and exit the loop.
            if (Item.Name == Name)
            {
                return Item;
            }
            else
            {
                // Otherwise, throw an exception to indicate that the ball wasn't found.
                throw new KeyNotFoundException("The ball name doesn't exist.");
            }


        }
    }

Answer 1

Change your code to:

 foreach (BallData Item in _BallList)
 {
            //If the name matches, return the item to the caller and exit the loop.
            if (Item.Name == Name)
            {
                return Item;
            }

  }
  throw new KeyNotFoundException("The ball name doesn't exist.");