阅读以下程序,写出输出结果。
class Swap { void sw1 (Person x, Person y){ int a = y.id; y.id = x.id; x.id = a; } void sw2 (Person x, Person y){ Person e; e = x; y = x; x = e; } } public class Person { int id = 0; Person (int id) { this.id = id; } public static void main(String[] args) { Swap cid = new Swap (); Person p1 = new Person (10); Person p2 = new Person (11); Person p3 = new Person (12); Person p4 = new Person (13); cid.sw1(p1,p2); cid.sw2(p3,p4); System.out.println("p1: " + p1.id + "p2: " + p2.id); System.out.println("p3: " + p3.id + "p4: " + p4.id); } }