Classes Revisited - Learning Java Through Games - page 184

public Address () {

}

public Address( String streetName , int number) {

this . streetName = streetName ;
this . number = number ;

}

public String toString() {
return number + "" + streetName ;

}

public void changeAddress(String streetName , int number) {

this . streetName = streetName ;
this . number = number ;

}

public Object clone () throws CloneNotSupportedException {

Address result = (Address) super .clone();
result .streetName = new String(streetName) ;
return result ;

}

}

When we execute the program, we get: Superwoman lives at 123 Main .Thisismore
desirable behavior. The address of the fictional character c1 is changed, but this does not
lead to the change of the address of fictional character c2 . After all, the clone of Superwoman
may live down the street from the original Superwoman. The clone method inside the
FictionalCharacter class uses the clone method of the Object class. The latter method
just copies the data. Since the returned object must be of type Object , it needs to be
explicitly cast to a FictionalCharacter . In addition, we make a copy of the address object
by calling the clone method on the address object. Note that the Address class is now
rewritten to support the clone method.

8.13 Comparing Objects for Equality
Now that we know how to clone fictional characters, it is reasonable to ask ourselves
when two fictional characters are equal. In Java, the following code will compile.
Superhero s1 = new Superhero( "Superman" ,5,5) ;
Superhero s2 = new Superhero( "Superman" ,5,5) ;
if (s1 == s2) {
...
}
One might anticipate that the condition inside the if statement will be true because the two
superheroes have the same name , goodPower ,and respect . However, when “==” is used
to compare two objects, only their addresses are compared. In the above case, we clearly
have two distinct objects, and therefore the condition inside the if statement will be false.
If we need access to a more meaningful way of comparing two objects for equality, then
we need to override the equals method of the Object class. Since the equals method is