Whta ia the use of this in setter method. I get the same output witjout use of this keyword.

Question

public void setColor(String c) {
this.color = c;
}
public void setColor(String c) {
color = c;
}
how the above two are different?

Answer 1

1. It prevents shadowing (if you created a global variable named c you might use the argument c although you want to use the global variable).
2. Usually you will name the parameters of a constructor exactly like the attribute. Then you need to use this to tell the compiler what variable you want to use, example:

class MyClass {

String s;

public MyClass(String s) {
this.s=s;
}
}

Answer 2

There is no difference in your examples, because you named the parameter of the setter method not the same as the attribute.
But it's a best practice to do so. So you name the parameter of your setter method color and use
this.color=color;
in the methods body.
It's not a must, but setter methods are commonly written like that.

Answer 3

thank you. very much helpful

Answer 4

then is it like this keyword is necessary when it is constructor and not in setter?

Answer 5

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");Vehicle v2 = new Vehicle();
v2.setColor ("Blue");
System.out.println(v1.getColor());
System.out.println(v2.getColor());
}
}
this program gives me the same result when i assign the color attribute like this.color=c;

Answer 6

may i know how execution is different in these two scenarios?