Android: How to properly show and hide the virtual keyboard?

Question

Java

The application consists of one activity: a text field and two buttons (+ a pair of TextView).
Text field for the phone number, the first button (button A) is for data processing, the second (button B) is for clearing.
When you press button A, data is being processed, the keyboard is hidden so as not to interfere.
When you press the B button, everything unnecessary is removed, the keyboard is displayed, the cursor enters the text field.

Situation : the cursor is in the field, the "telephone" keyboard is displayed, I press the home button.
What happens : the application closes, the "telephone" keyboard is hidden, but the regular (letters and numbers) keyboard continues to be displayed (as if it were hanging there as a second layer) and is hidden only by pressing the back key.
Question: how to make the alphanumeric keyboard not appear? Where did she come from? Maybe I caused something extra somewhere? Or do I specify the wrong parameter (flag) in inputMethodManager?

Maybe I'm initially calling the keyboard show incorrectly?

I would be grateful if you tell me where the error is.
Link to Github: https://github.com/StepanMe/PhoneInfo/blob/master/...