内部类的继承和初始化顺序

//: BigEgg2.java
// Proper inheritance of an inner class
import java.io.*;
class Egg2 {
 protected class Yolk {
  public Yolk() {
   System.out.println("Egg2.Yolk()");
  }
  public void f() {
   System.out.println("Egg2.Yolk.f()");
  }
 }
 
 public Yolk y = new Yolk();

 public Egg2() {
  System.out.println("New egg()2");
 }
 public void insertYolk(Yolk yy) {
  y = yy;
 }
 public void g() {
  y.f();
 }
}
public class BigEgg2 extends Egg2 {
 public class Yolk extends Egg2.Yolk {
  public Yolk() {
   System.out.println("BigEgg2.Yolk()");
  }
  public void f() {
   System.out.println("BigEgg2.Yolk.f()");
  }
 }
 public BigEgg2() {
  //insertYolk(new Yolk());
  new Yolk();
 }
 public static void main(String[] args) {
  Egg2 e2 = new BigEgg2();
  //e2.g();
 }
}
从输出结果来看：

初始化顺序如下：
先初始化父类成员变量，然后父类构造函数，然后子类成员变量，子类构造函数