Zi是Fu 的子类 ，问题如下 Fu f=new Zi() Zi z=new Zi() 是不是可以说 Fu f=Zi z

abstract class Teacher{
public abstract void show();
}
class Per {
public void method(Teacher t){//Teacher t=new Tea();
t.show();
}
}
class Tea extends Teacher{
public void show(){
System.out.println("show");
}
public void method(){
System.out.println("method");
}
}
public class Person {
public static void main(String[] args) {

Per p=new Per();
Teacher t=new Tea();//用这个也可以 Tea t=new Tea();
p.method(t);
}
}

相关了解……