Java Comparator

Student.java

// Comparable interface allows us to sort the objects according to the natural
// order. For example, you want to sort a bunch of strings. The natural order
// would be to sort them accroding to their Case sensitivity (Unicode).

// But what if you want to convey a message to the sort algorithm that you want
// to sort the strings in an case insensitive way. The way you do that is by using
// comparators.

// Alright, there are two entities here.
// An class which implements whose objects are to be compared.
// A sorting class that compares the comparable types.

// To implement a comparator interface to your class, you need to
//  * Create a nested class that implements the comparator interface.
//  * implement the compare method.
//  * Create a static final Comparator object of the class that implements the
//    comparable interface.

// The sorting algorithm class will take the comparator object and invoke the
// compare method on two comparable objects.
// MergeSort.sort(array, Student.BY_NAME);
// MergeSort.sort(array, Student.BY_SECTION);


import java.util.Comparator;

public class Student implements Comparable<Student> {
	private String name;
	private int section;

	public static final Comparator<Student> BY_NAME = new ByName();
	public static final Comparator<Student> BY_SECTION = new BySection();

	public int compareTo(Student that) {
		return 0;
	}
	private static class ByName implements Comparator<Student> {
		public int compare(Student one, Student two) {
			return one.compareTo(two);
		}
	}

	private static class BySection implements Comparator<Student> {
		public int compare(Student one, Student two) {
			return one.section = two.section;
		}
	}
}