紧急求助java问题给解答一下

//Person类，其中包括姓名（String：name），性别（char：sex），年龄（int：age），
// 类中声明构造方法以及get和set方法设置person对象的姓名、性别、年龄。
public class Person {

    private String name;

    private char sex;

    private int age;

    public Person(String name, char sex, int age) {
        this.name = name;
        this.sex = sex;
        this.age = age;
    }

    public Person() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public char getSex() {
        return sex;
    }

    public void setSex(char sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}




//定义Person类的子类 Teacher ，Teacher类中增加职称（int：Tech_title,一共三个等级1，2，3），工资（int:salary）,
// 声明构造方法以及set和get方法设置职称和工资，
// 其中工资是根据等级计算出来的，一级4000元，二级5000元，三级6000元。
public class Teacher extends Person{

    int tech_title;

    int salary;

    public Teacher(){}

    public int getTech_title() {
        return tech_title;
    }

    public void setTech_title(int tech_title) {
        this.tech_title = tech_title;
    }

    public int getSalary() {
        int calcuSalary = 0;
        switch (getTech_title()){
            case 1:{
                calcuSalary = 4000;break;
            }
            case 2:{
                calcuSalary = 5000;break;
            }
            case 3:{
                calcuSalary = 6000;break;
            }
        }
        return salary<=0?calcuSalary:salary;
    }

    public void setSalary(int salary) {
        this.salary = salary;
    }

    @Override
    public String toString() {
        return getName()+" "+getSex()+" "+getAge()+" "+getSalary();
    }
}

//测试类
public class Test {

    public static void main(String[] args) {
        Teacher teacher = new Teacher();
        teacher.setName("张老师");
        teacher.setSex('女');
        teacher.setAge(30);
        teacher.setTech_title(2);
        System.out.println(teacher);
    }
}