instead of xpath what can i select from the below code - selenium

Question

Please help me to find locator in this case as id is dynamic and it changes every time when I refresh the page.
type="text" also I will not be able to use because, for the next fields, eveything is same from the down code except, the label changes from the "first name" to the "last name" and so on.
So I should be selecting something in terms of the first name which is mentioned in the label tag below.
Please anyone can help me in this case.
<input class="md-input-element ng-valid ng-dirty ng-touched" id="md-
input-4-input" spellcheck="false" type="text">
<!--template bindings={}-->
<label class="md-input-placeholder md-float md-empty" for="md-input-
4-input">First name * <!--template bindings={}--></label>

Answer 1

You can use preceding-sibling or following-sibling feature from xpath. As per code mentioned above your xpath should be like this:
//input[#type='text'][following-sibling::label[contains(text(),'First name')]]
But I think in html label should be first then input, if that is case please try below one:
//input[#type='text'][preceding-sibling::label[contains(text(),'First name')]]

Answer 2

you can get the css selector from the class (can't do by className if it has spaces in the class name so use css, put a "." at the beginning and replace any spaces with a ".")
#FindBy(css = ".md-input-element.ng-valid.ng-dirty.ng-touched")
private WebElement elementMDInputTouched;
#FindBy(css = ".md-input-placeholder.md-float.md-empty")
private WebElement elementMDInputEmpty;