Fix #747 : Added Checks for empty Edittexts and for validity of Url in Update Endpoints Setting

[miPlodder]

Fixes #747

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[miPlodder]

@therajanmaurya @dilpreet96 @satyan @droidchef Please review this PR.

[luckyman20]

It should be Base URL

[miPlodder]

@luckyman20 I have used "Base Url" because the Title also shows "Base Url". It's better to have consistency in messages.

[luckyman20]

@miPlodder I think you can change that too also because URL is a short form for Uniform Resource Locater & short forms should be written in caps only.

[luckyman20]

@miPlodder Another approach you can use that check all the things when OK button is clicked, it will shorten the code.

You should also check whether it is a valid URL or not

[miPlodder]

@luckyman20 I have made a check for validity of the URL. Moreover, when OK button is pressed, then the AlertDialog closes, we cannot prevent this behaviour, please refer this abstract class PreferenceDialogFragmentCompat, where it creates iAlert dialog and we are using it.

Moreover, it's good approach to give continuous feedback to user in forms where lesser number of fields are available. That's why I have used TextWatcher.

[therajanmaurya]

Fix conflicts.

[miPlodder]

@therajanmaurya Please review this PR again.