UsingComparable1.java

package genericsAndCollections;

/**
 * 
 * @author chengfeili 
 * Jun 7, 2017 9:07:21 PM
 *
 *         Remember that id – a.id sorts in ascending order and a.id – id sorts
 *         in descending order.
 */
public class UsingComparable1 implements Comparable<UsingComparable1> {
	private int id;

	public int compareTo(UsingComparable1 a) {
		return this.id - a.id;
	}

	public static void main(String[] args) {
		UsingComparable1 a1 = new UsingComparable1();
		UsingComparable1 a2 = new UsingComparable1();
		a1.id = 5;
		a2.id = 7;
		System.out.println(a1.compareTo(a2)); // -2
		System.out.println(a1.compareTo(a1)); // 0
		System.out.println(a2.compareTo(a1)); // 2
	}
}