Mega Code Archive
Generic Comparable
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import java.util.Arrays;
import java.util.Comparator;
class Person implements Comparable<Person> {
public Person(String firstName, String surname) {
this.firstName = firstName;
this.surname = surname;
}
public String getFirstName() {
return firstName;
}
public String getSurname() {
return surname;
}
public String toString() {
return firstName + " " + surname;
}
public int compareTo(Person person) {
int result = surname.compareTo(person.surname);
return result == 0 ? firstName.compareTo(((Person) person).firstName) : result;
}
private String firstName;
private String surname;
}
class ComparePersons implements Comparator<Person> {
// Method to compare Person objects - order is descending
public int compare(Person person1, Person person2) {
int result = -person1.getSurname().compareTo(person2.getSurname());
return result == 0 ? -person1.getFirstName().compareTo(person2.getFirstName()) : result;
}
// Method to compare with another comparator
public boolean equals(Object collator) {
if (this == collator) { // If argument is the same object
return true; // then it must be equal
}
if (collator == null) { // If argument is null
return false; // then it can't be equal
}
return getClass() == collator.getClass(); // Class must be the same for
// equal
}
}
public class MainClass {
public static void main(String[] args) {
Person[] authors = { new Person("A", "S"),
new Person("J", "G"),
new Person("T", "C"),
new Person("C", "S"),
new Person("P", "C"),
new Person("B", "B") };
System.out.println("Original order:");
for (Person author : authors) {
System.out.println(author);
}
Arrays.sort(authors, new ComparePersons()); // Sort using comparator
System.out.println("\nOrder after sorting using comparator:");
for (Person author : authors) {
System.out.println(author);
}
Arrays.sort(authors); // Sort using Comparable method
System.out.println("\nOrder after sorting using Comparable method:");
for (Person author : authors) {
System.out.println(author);
}
}
}
Original order:
A S
J G
T C
C S
P C
B B
Order after sorting using comparator:
C S
A S
J G
T C
P C
B B
Order after sorting using Comparable method:
B B
P C
T C
J G
A S
C S
]]>