import java.util.*;


// The class we define for "Person" objects:

class Person implements Comparable<Person> {

    // Some data:
    String firstName;
    String lastName;
    int birthYear;
    
    // We'll use this to decide what kind of sorting we want.
    public boolean sortByAge = false;


    // This is called a constructor:

    public Person (String firstName, String lastName, int birthYear)
    {
        this.firstName = firstName;
        this.lastName = lastName;
        this.birthYear = birthYear;
    }


    // To allow for printing via System.out.println:

    public String toString ()
    {
        return "Person: " + firstName + " " + lastName + " (b. " + birthYear + ")";
    }
    


    // A comparison method to allow two Person instances to be compared.

    public int compareTo (Person d)
    {
        // Check if object passed in is of correct type.
        if (! (d instanceof Person) ) {
            return -1;
        }
        
        // Cast to a Person variable so that we can access fields.
        Person p = (Person) d;

        if (sortByAge) {
            // Compare ages.
            if (birthYear < p.birthYear) {
                return -1;
            }
            else if (birthYear > p.birthYear) {
                return 1;
            }
            else {
                return 0;
            }
            
        }
        else {
            // Sort alphabetically by name, starting with lastname.
            if ( lastName.compareTo (p.lastName) < 0 ) {
                return -1;
            }
            else if ( lastName.compareTo (p.lastName) > 0 ) {
                return 1;
            }
            
            // If last names are equal, try first names.
            if ( firstName.compareTo (p.firstName) < 0 ) {
                return -1;
            }
            else if ( firstName.compareTo (p.firstName) > 0 ) {
                return 1;
            }
            else {
                return 0;
            }
        }
    }

} //end-Person




public class ObjectSortExample4 {

    public static void main (String[] argv)
    {
        Person[] someKennedys = new Person [10];

        Person p = new Person ("Patrick", "Kennedy", 1858);

        System.out.println ("First one: " + p);
        someKennedys[0] = p;
        
        // Do the others:
        someKennedys[1] = new Person ("Joseph", "Kennedy", 1888);
        someKennedys[2] = new Person ("Rose", "Fitzgerald", 1890);
        someKennedys[3] = new Person ("Joseph", "Kennedy", 1915);
        someKennedys[4] = new Person ("John", "Kennedy", 1917);
        someKennedys[5] = new Person ("Jacqueline", "Bouvier", 1929);
        someKennedys[6] = new Person ("Robert", "Kennedy", 1925);
        someKennedys[7] = new Person ("Edward", "Kennedy", 1932);
        someKennedys[8] = new Person ("Caroline", "Kennedy", 1957);
        someKennedys[9] = new Person ("Maria", "Shriver", 1955);

        System.out.println ("Unsorted: ");
        print (someKennedys);

        System.out.println ("Sorted: ");
        Arrays.sort (someKennedys);
        print (someKennedys);
        
        // We want to sort by age, so set that flag in all instances.
        for (int i=0; i<someKennedys.length; i++) {
            someKennedys[i].sortByAge = true;
        }

        System.out.println ("Sorted by age: ");
        Arrays.sort (someKennedys);
        print (someKennedys);
        
    }



    static void print (Person[] people)
    {
        for (int i=0; i<people.length; i++) {
            // people[i] is a Person instance.
            System.out.println (people[i]);
        }
    }
    
}