c类是a类的引用类，当C 类指向B类是可以调用B类从A类继承方法和变量，但不能调用，B类新增的方法和变量

class DuiXiang1 extends DuiXiang{

String eadder;

void print(){

System.out.println("住址"+eadder);

}

}

public class DuiXiang{

String ename;

int eid;

int eage;

public String eadder;

void print(){

System.out.println("姓名"+ename+"ID号"+eid+"年龄"+eage);

}

}

public class Text {

public static void main(String args[]){

DuiXiang a1=new DuiXiang1();

DuiXiang a2=new DuiXiang1();

a1.ename="wanger";

a1.eid=14;

a1.eage=22;

System.out.println("这是一个父类的引用指向子类的象");

a1.print();

a2.eadder="shanghaishi";

a2.print();

}

}