Is "this" necessary within getter and setter?

Question

Why does the following code work, even if I don't use the keyword "this" to refer to the current object?
public class Vehicle {
private String color;
// Getter
public String getColor() {
return color;
}
// Setter
public void setColor(String c) {
color = c;
}
}
class Program {
public static void main(String[ ] args) {
Vehicle v1 = new Vehicle();
v1.setColor("Red");
System.out.println(v1.getColor());
}
}

Answer 1

it's necessary if you use the same names. for example if you write in setColor string color, you must use "this"