构造函数顺序

class X
{
    X()
    {
        System.out.println("x");            //2
    }    
    Y y=new Y();                            //1
}
class Y
{

    Y()
    {
        System.out.println("y");
    }
}
 class Z extends X{

    /**
     * @param args
     */
     Y y=new Y();            //3
    Z()
    {
        System.out.println("z");            //4
    }
    public static void main(String[] args)
    {
        // TODO Auto-generated method stub
        new Z();
    }

}