I have a Fraction class using keyword this in my constructor:
public Fraction(int numerator, int denominator) { this.numerator = numerator; this.
Both the cases you mentioned will work fine.
Use of this is a good practice as its more readable due to our english mindset, When we say this.some_variable, we get a mental image of some_variable inside the current class
this
this.some_variable
this keyword is also helpful in avoiding variable shadowing