求一个Java的程序，要求表现多态特征，且要有抽象类被若干个子类继承?????

public abstract class test{
public void aMethod(){
System.out.println("父类test方法");
}
}
class test1 extends test{
public test1(){
System.out.println("test1构造函数");
}
public void aMethod(){
System.out.println("子类test1方法");
}
}
class test2 extends test{
public test2(){
System.out.println("test2构造函数");
}
public void aMethod(){
System.out.println("子类test2方法");
}
}
class Main{
public static void main(String[] args){
test1 t1=new test1();
test2 t2=new test2();
t1.aMethod();
t2.aMethod();
test opp=new test1(); //多态调用
test t=t1; //多态调用
t.aMethod();
test tt=t2; //多态调用
tt.aMethod();
}
}

------------父类----------------
public abstract class Father {

public abstract void say();
public void say(String s){
System.out.println(s);
}
}