Re: compareTo question
maxnesler@gmail.com wrote:
I have been reviewing java for a class this winter, and i noticed in
more than a few code examples that compareTo calls itself? Is this a
"different" compareTo; from another object? Im confused. I also did
indeed read the javadoc.
compareTo() doesn't call itself. That can happen but in this case it doesn't.
compareTo() is an instance method - it belongs to a particular object. You
have a compareTo() that belongs to a specific Employee object calling the
compareTo() that belongs to a particular String object.
this is not my code, i cut and pasted from an example on the web.
class Employee implements Comparable {
String department, name;
These particular String objects sport their own individual compareTo() methods.
.... skipping to juicy part ...
public int compareTo(Object obj) {
Employee emp = (Employee) obj;
We convert via a class cast the 'obj' pointer into an 'emp' pointer. 'emp'
knows about 'Employee' methods that 'obj' cannot comprehend. Incidentally,
this cast runs the risk of throwing a ClassCastException.
int deptComp =
department.compareTo(emp.getDepartment());
This here is the 'compareTo()' that belongs specifically to the 'department'
String member of 'this', not the whole 'Employee' object.
return ((deptComp == 0) ? name.compareTo(emp.getName()) :
deptComp);
This here is the 'compareTo()' that belongs specifically to the 'name' String
member of 'this', not the whole 'Employee' object.
Notice the '.' (dot) operator that connects the variable to the method call.
That tells you who owns the method that's being called.
--
Lew