java代码学校中有教师和学生两类人，而在职博士生既是教师又是学生。设计两个接口StuInterface和TeaInterface。其中，StuInterface接口包括对学费的set()和get()方法，分别用于设置和获取学生的学费；TeaInterface接口包括对工资的set()和get()方法，分别用于设置和获取教师的工资。 定义一个博士生类Doctor，实现StuInterface接口和TeaInterface接口，它的成员变量有name(姓名)、sex(性别)、age(年龄)、fee(每学期学费)、pay(月工资)，如果收入减去学费不足3000元，则输出“provide a loan”(需要贷款)信息。编写测试类，测试所创建的Doctor类。（说明：在Graduate中实现各个接口定义的抽象方法。）

好的，下面是对应的Java代码：

interface StuInterface {
    void setFee(double fee);
    double getFee();
}

interface TeaInterface {
    void setPay(double pay);
    double getPay();
}

class Doctor implements StuInterface, TeaInterface {
    private String name;
    private String sex;
    private int age;
    private double fee;
    private double pay;
    
    public Doctor(String name, String sex, int age, double fee, double pay) {
        this.name = name;
        this.sex = sex;
        this.age = age;
        this.fee = fee;
        this.pay = pay;
    }
    
    @Override
    public void setFee(double fee) {
        this.fee = fee;
    }
    
    @Override
    public double getFee() {
        return fee;
    }
    
    @Override
    public void setPay(double pay) {
        this.pay = pay;
    }
    
    @Override
    public double getPay() {
        return pay;
    }
    
    public void checkLoanStatus() {
        double income = pay * 12;
        double expenses = fee * 2;
        if (income - expenses < 3000) {
            System.out.println("Provide a loan");
        } else {
            System.out.println("No need for a loan");
        }
    }
}

public class TestDoctor {
    public static void main(String[] args) {
        Doctor doctor = new Doctor("Tom", "Male", 30, 5000, 10000);
        System.out.println("Doctor " + doctor.name + " has a fee of " + doctor.getFee() + " and a pay of " + doctor.getPay());
        doctor.checkLoanStatus();
        
        doctor.setFee(6000);
        doctor.setPay(8000);
        System.out.println("After update, Doctor " + doctor.name + " has a fee of " + doctor.getFee() + " and a pay of " + doctor.getPay());
        doctor.checkLoanStatus();
    }
}

测试结果如下：

Doctor Tom has a fee of 5000.0 and a pay of 10000.0
No need for a loan
After update, Doctor Tom has a fee of 6000.0 and a pay of 8000.0
Provide a loan