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Java Comparable example.
This Java Comparable
example describes how java.util.Comparable interface is implemented
to compare user defined
classe's objects.
*/
import java.util.*;
/*
Comparable interface
is used to make user defined class's objects comparable.
This interface declares
one method compareTo(Object object) and determines how ojbects
can be compared to each
other.
*/
/*
Implement java.util.Comparable
interface to make class objects comparable.
*/
class Employee implements
Comparable{
private
int age;
public
void setAge(int age){
this.age=age;
}
public
int getAge(){
return this.age;
}
/*
Signature of compareTo
method is.
public int compareTo(Object
object).
compareTo method should
return 0 if both objects are equal, 1 if first grater than other
and -1 if first less than the other object of the same class.
*/
public
int compareTo(Object
otherEmployee){
/*
If passed object is
of type other than Employee, throw ClassCastException.
*/
if( ! ( otherEmployee instanceof
Employee )
){
throw new
ClassCastException("Invalid
object");
}
int age = ( (Employee) otherEmployee
).getAge();
if( this.getAge()
> age
)
return 1;
else if
( this.getAge() < age )
return -1;
else
return 0;
}
}
public class JavaComparableExample{
public
static void
main(String args[]){
/*
Create two different
Employee objects, so that we can compare both.
*/
Employee one = new Employee();
one.setAge(40);
Employee two = new Employee();
one.setAge(30);
/*
Use compareTo method
to determine which employee is younger
*/
if( one.compareTo(two) >
0 )
{
System.out.println("Employee
one is elder than employee two !");
} else if( one.compareTo(two)
< 0
) {
System.out.println("Employee
one is younger than employee two !");
} else( one.compareTo(two)
== 0
) {
System.out.println("Both
employees are same !");
}
}
}
/*
OUTPUT of the above
given Java Comparable Example would be :
Employee one is elder
than employee two !
*/
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