Each OnClickListener can be a default anonymous class, that will be triggered only by one button. So no need to name them "NegativeClickEvent", "DoublezeroClickEvent", etc.
You can keep a boolean variable if the "." was pressed, and accept another one only if not. If you want a usable calculator, you need a "backspace" button as well. So note that the dot may be deleted. (need to keep track of its placement).
For the leading 0, you can use a simple "if dot was pressed first, insert 0.".
There are many ways to implement what you want, but to keep it simple, just handle the cases you need to handle.
Other ways to implement this may include Double.parseDouble(s) with catch (NumberFormatException e) on each key pressed, or using a double as your buffer, and using the buttons to perform mathematical operations on it directly (such as multiply by 10 and adding the new digit on each button press) - this will ensure input validity without the need to parse String, but it's more complicated to implement.