class Person {

    // Some data:
    String firstName;
    String lastName;
    int birthYear;
    

    // This is called a constructor:

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


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

    public boolean lessThan (Person p)
    {
        // Compare the birthyear inside this instance (where we are executing)
        // with the birthyear of the parameter instance.
        if (birthYear < p.birthYear) {
            return true;
        }
        else {
            return false;
        }
    }
    
} // end-of-Person




public class ObjectSortExample {

    public static void main (String[] argv)
    {
        // Make space for 10 person pointers.
        Person[] someKennedys = new Person [10];

        // Each array location is itself an object pointer. We
        // need to assign actual object instances using the new operator.
        someKennedys[0] = new Person ("Patrick", "Kennedy", 1858);
        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);

        sort (someKennedys);

        System.out.println ("\nSorted: ");
        print (someKennedys);
    }


    static void print (Person[] people)
    {
        for (int i=0; i<people.length; i++) {
            System.out.println (people[i].firstName + " " + people[i].lastName + " (b. " + people[i].birthYear + ")");
        }
    }
    

    static void sort (Person[] people)
    {
        // Selection Sort.

	for (int i=0; i<people.length-1; i++) {
	    Person min = people[i];
	    int pos = i;
	    for (int j=i+1; j<people.length; j++) {
		if ( people[j].lessThan (min) ) {
		    min = people[j];
		    pos = j;
		}
	    }

	    // Swap.
	    Person temp = people[i];
	    people[i] = people[pos];
	    people[pos] = temp;
	}
    }

} // end-of-ObjectSortExample