Best compareTo

import junit.framework.TestCase;public class PersonSummaryTest extends TestCase implements Comparable<PersonSummaryTest>{	private Integer id; 		public static void main(String[] args) {		junit.textui.TestRunner.run(PersonSummaryTest.class);	}	public void testCompareTo() {		PersonSummaryTest pSum1 = new PersonSummaryTest();		PersonSummaryTest pSum2 = new PersonSummaryTest();				pSum1.setId(1);		pSum2.setId(1);		assertEquals(0, pSum1.compareTo(pSum2));				pSum2.setId(2);		assertEquals(-1, pSum1.compareTo(pSum2));				pSum2.setId(0);		assertEquals(1, pSum1.compareTo(pSum2));	}	public int compareTo(PersonSummaryTest p) {		return id != null ? id.compareTo(p.getId()) : p != null ? p.compareTo(this) : 0;	}	public Integer getId() {		return id;	}	public void setId(Integer id) {		this.id = id;	}	}