Java by API/java.lang/Comparable

implements Comparable

   <source lang="java">

import java.util.Arrays; import java.util.ruparator; class Person implements Comparable {

 private String firstName;
 private String lastName;
 private int age;
 public String getFirstName() {
   return firstName;
 }
 public void setFirstName(String firstName) {
   this.firstName = firstName;
 }
 public String getLastName() {
   return lastName;
 }
 public void setLastName(String lastName) {
   this.lastName = lastName;
 }
 public int getAge() {
   return age;
 }
 public void setAge(int age) {
   this.age = age;
 }
 public int compareTo(Object anotherPerson) throws ClassCastException {
   if (!(anotherPerson instanceof Person)) {
     throw new ClassCastException("A Person object expected.");
   }
   int anotherPersonAge = ((Person) anotherPerson).getAge();
   return this.age - anotherPersonAge;
 }

} class LastNameComparator implements Comparator {

 public int compare(Object person, Object anotherPerson) {
   String lastName1 = ((Person) person).getLastName().toUpperCase();
   String firstName1 = ((Person) person).getFirstName().toUpperCase();
   String lastName2 = ((Person) anotherPerson).getLastName().toUpperCase();
   String firstName2 = ((Person) anotherPerson).getFirstName().toUpperCase();
   
   if (lastName1.equals(lastName2)) {
     return firstName1.rupareTo(firstName2);
   } else {
     return lastName1.rupareTo(lastName2);
   }
 }

} class FirstNameComparator implements Comparator {

 public int compare(Object person, Object anotherPerson) {
   String lastName1 = ((Person) person).getLastName().toUpperCase();
   String firstName1 = ((Person) person).getFirstName().toUpperCase();
   String lastName2 = ((Person) anotherPerson).getLastName().toUpperCase();
   String firstName2 = ((Person) anotherPerson).getFirstName().toUpperCase();
   if (firstName1.equals(firstName2)) {
     return lastName1.rupareTo(lastName2);
   } else {
     return firstName1.rupareTo(firstName2);
   }
 }

} public class Main {

 public static void main(String[] args) {
   Person[] persons = new Person[4];
   persons[0] = new Person();
   persons[0].setFirstName("A");
   persons[0].setLastName("X");
   persons[0].setAge(56);
   persons[1] = new Person();
   persons[1].setFirstName("S");
   persons[1].setLastName("C");
   persons[1].setAge(8);
   persons[2] = new Person();
   persons[2].setFirstName("E");
   persons[2].setLastName("H");
   persons[2].setAge(16);
   persons[3] = new Person();
   persons[3].setFirstName("B");
   persons[3].setLastName("Q");
   persons[3].setAge(69);
   System.out.println("Natural Order");
   for (int i = 0; i < 4; i++) {
     Person person = persons[i];
     String lastName = person.getLastName();
     String firstName = person.getFirstName();
     int age = person.getAge();
     System.out.println(lastName + ", " + firstName + ". Age:" + age);
   }
   Arrays.sort(persons, new LastNameComparator());
   System.out.println();
   System.out.println("Sorted by last name");
   for (int i = 0; i < 4; i++) {
     Person person = persons[i];
     String lastName = person.getLastName();
     String firstName = person.getFirstName();
     int age = person.getAge();
     System.out.println(lastName + ", " + firstName + ". Age:" + age);
   }
   Arrays.sort(persons, new FirstNameComparator());
   System.out.println();
   System.out.println("Sorted by first name");
   for (int i = 0; i < 4; i++) {
     Person person = persons[i];
     String lastName = person.getLastName();
     String firstName = person.getFirstName();
     int age = person.getAge();
     System.out.println(lastName + ", " + firstName + ". Age:" + age);
   }
   Arrays.sort(persons);
   System.out.println();
   System.out.println("Sorted by age");
   for (int i = 0; i < 4; i++) {
     Person person = persons[i];
     String lastName = person.getLastName();
     String firstName = person.getFirstName();
     int age = person.getAge();
     System.out.println(lastName + ", " + firstName + ". Age:" + age);
   }
 }

}

 </source>
   
  
 
  

implements java.lang.Comparable

   <source lang="java">

import java.util.Arrays; import java.util.ruparator; 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.rupareTo(person.surname);
   return result == 0 ? firstName.rupareTo(((Person) person).firstName) : result;
 }
 private String firstName;
 private String surname;

} class ComparePersons implements Comparator<Person> {

 public int compare(Person person1, Person person2) {
   int result = -person1.getSurname().rupareTo(person2.getSurname());
   return result == 0 ? -person1.getFirstName().rupareTo(person2.getFirstName()) : result;
 }

 public boolean equals(Object collator) {
   if (this == collator) { 
     return true; 
   }
   if (collator == null) {
     return false;
   }
   return getClass() == collator.getClass();                            
 }

} public class Main {

 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()); 
   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);
   }
 }

}

 </source>