Java Reference
In-Depth Information
this.name = personName;
}
}
In this simple
Person
class, each
Person
has a
name
, which is stored as a
String
variable. The
constructor has a
String
parameter that's assigned to the
Person
is name variable when it is con-
structed. Here, you can read the constructor as “the name variable of
this
person object being con-
structed should be given the value of the
personName String
provided as a parameter.”
public void printName(){
System.out.println(this.name);
}
If you add an instance method to print the name of a
Person
object, you can use the
this
keyword
to identify which name should be printed: “the value assigned to the name variable of
this
Person
object whose method is being called.”
These examples should illustrate how the
this
keyword is used. You might be wondering why you would
use it. After all, you could leave it out of the examples and they would function exactly the same way.
public class Person {
String name;
public Person(String personName){
name = personName;
}
public void printName(){
System.out.println(name);
}
}
As you can see, the use of the
this
keyword is optional in this situation. It is recommended that you
use it to be explicit and avoid ambiguity, but you could leave it out without impacting your program.
However, there are cases where you must use the
this
keyword. This is usually when a local vari-
able and an instance variable have the same name. Consider the following example:
public class Person {
String name;
public Person(String name){
name = name;
}
public void printName(){
System.out.println(name);
}
}
If you try this in Eclipse, you'll see a warning:
The assignment to variable name has no
effect
. In this case, because
name
is a local variable for the constructor method, you will be refer-
ring to this local variable if you refer to
name
inside the method. Essentially, you are saying the
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