Number类定义如下：public class Number { public int x; }swap方法定义如下：public static void swap(Number number1, Number number2) { int temp = number1.x; number1.x = number2.x; number2.x = temp; }运行如下代码： Number number1 = new Number(); Number number2 = new Number(); Number number3 = new Number(); number1.x = 1; number2.x = 2; number3.x = 3; swap(number1, number2); swap(number2, number3);则number1.x, number2.x, number3.x的值分别为：A:1, 2, 3 B:2, 3, 1 C:3, 2, 1 D:1, 3, 2 答案: 2, 3, 1