Abstract class name as formal parameter

/**
 * abstract class name as formal parameter
 * @author Administrator
 *
 */
//Define a human abstract class
abstract class Person{
	public abstract void study();
}
class PersonDemo{
	public void method(Person p){//p; p = new Student(); Person p = new Student //多态
		p.study();
	}
}
//Define a concrete class to implement this abstract class
class StudentQ extends Person{

	@Override
	public void study() {
		// TODO Auto-generated method stub
		System.out.println("Study hard");
	}
	
}

public class AbstractTest {
	public static void main(String[] args){
		// Currently there is no way to use
		//Because the abstract class has no corresponding concrete class
		//Then, we should first define a concrete class
		//Requirement: I want to use the method method in PersonMdemo
		PersonDemo pd =new PersonDemo();
		StudentQ s = new StudentQ();
		pd.method(s);
	}
}