Delving Further into Object-Oriented Concepts - Beginning Java Programming: The Object-Oriented Approach - page 226

local String name should be assigned the value it already has, and you have done nothing with the
instance variable name of the Person object. You must use the this keyword inside the constructor
to refer to the instance variable name. You are not required to use it in the printName() method,
but it is recommended to avoid ambiguity.

public class Person {
String name;
public Person(String name){
this.name = name;
}
public void printName(){
System.out.println(name);
}
}

Another case where you may need to use the this keyword is when you have overloaded the con-
structor method and want to explicitly call one constructor from within another constructor.
Imagine, for instance, that sometimes you need to construct a Person object but you do not know
their name. You could create another constructor with no parameters and use the this keyword to
call the one String parameter constructor with a default name.

public class Person {
String name;
public Person(){
this("Unknown");
}
public Person(String name){
this.name = name;
}
public void printName(){
System.out.println(name);
}
}

Again, you might think the this keyword is not necessary, as for this simple example, you could
make a no‐parameter constructor that assigns the name variable to "Unknown" itself, without using
the this keyword. However, when your constructor is more complex, with several statements and
perhaps some calculations, using the this keyword will limit redundancy, increase readability, and
prevent discrepancies between what different constructors accomplish. The next exercise allows you
to try method overloading using the this keyword.

Method Overloading

try it out

In this exercise, you expand the Person class from the examples to demonstrate the use of method over-
loading and the this keyword.
1.

If you do not already have a project in Eclipse for Chapter 7, create one now.