课堂练习2：大学里的学生（Student）需要交学费，而研究生（Graduate）作为学生比较特殊，除了需要交学费外，还可以获取一部分科研津贴，由学校（University）统一发放。此外，学校还需要

public abstract class Student {String name;int fee;Student(String name){    this.name=name;} abstract void setFee(int fee); abstract int getFee();}

public interface Salary {public abstract int getSalary();    }

public class Graduate extends Student implements Salary {Graduate(String name) {    super(name);    }public int salary; void Graduate(String name){} void setFee(int fee){ }int getFee(){    return fee;}public int getSalary(){    return 1500;}boolean isLoan(){    if(salary<fee) {        System.out.println("需要贷款");    return true;}    else         return false;}   }

public class Teacher implements Salary{String name;int salary;Teacher(String name){}public int getSalary(){    return 3000;}}

public class University {void payOff1(Salary s){    System.out.println("研究生所得工资为："+s.getSalary());}void payOff2(Salary m){    System.out.println("老师所得工资为："+m.getSalary());}}

public class Test {    public static void main(String[] args) {        // TODO Auto-generated method stub        Graduate g=new Graduate("小亮");            g.setFee(1000);         University u=new University();        u.payOff1(g);        System.out.println("是否需要贷款:"+g.isLoan());        Teacher t=new Teacher("大王");        u.payOff2(t);    }}