没有运行结果，麻烦老师看下是怎么回事，谢谢

package com.office.info;
/*
 * 创建部门类
 */
public class department{
	private String departmentnum;//部门编号
	private String departmentname;//部门名称
	private staff[] departmentstaff;//部门员工信息
	public department(String departmentnum,String departmentname,staff[] departmentstaff){
		this.setDepartmentnum(departmentnum);
		this.setDepartmentname(departmentname);
		this.setDepartmentstaff(departmentstaff);
	}
	public String getDepartmentnum(){
		return departmentnum;
	}
	public void setDepartmentnum(String departmentnum) {
		this.departmentnum = departmentnum;
	}
	public String getDepartmentname() {
		return departmentname;
	}
	public void setDepartmentname(String departmentname) {
		this.departmentname = departmentname;
	}
	
	public staff[] getDepartmentstaff() {
		return departmentstaff;
	}
	public void setDepartmentstaff(staff[] departmentstaff) {
		this.departmentstaff = departmentstaff;
	}
	/*
	 * 统计该部门员工个数
	 */
	public int count(staff[] staff){
		int count=0;
		for(int i=0;i<staff.length;i++){
			if(staff[i]!=null){
				count++;
			}
		}
		return count;
	}
	
}


package com.office.info;
/*
 * 创建职务类
 */
public class duty {
	private String dutynum;//职务编号
	private String dutyname;//职务名称
	public duty(String dutynum,String dutyname){
		this.setDutynum(dutynum);
		this.setDutyname(dutyname);
	}
	public String getDutynum() {
		return dutynum;
	}
	public void setDutynum(String dutynum) {
		this.dutynum = dutynum;
	}
	public String getDutyname() {
		return dutyname;
	}
	public void setDutyname(String dutyname) {
		this.dutyname = dutyname;
	}
	
}



package com.office.info;
/*
 * 创建员工类
 */
public class staff {
	private String staffname;//员工姓名
	private String staffnum;//员工工号
	private int age;//员工年龄
	private String sex;//员工性别
	private department depart;//所属部门
	private String du;//职务信息
	
	public staff(String staffname,String staffnum,String sex,int age,String du){
		this.setStaffname(staffname);
		this.setStaffnum(staffnum);
		this.setAge(age);
		this.setSex(sex);
		this.setDu(du);
	}

	public String getStaffname() {
		return staffname;
	}
	public void setStaffname(String staffname) {
		this.staffname = staffname;
	}
	public String getStaffnum() {
		return staffnum;
	}
	public void setStaffnum(String staffnum) {
		this.staffnum = staffnum;
	}
	public int getAge() {
		return age;
	}
	/*
	 * 限定年龄只能是18--65之间,反之则设置默认为18岁
	 */
	public void setAge(int age) {
		if(this.age>=18&&this.age<=65){
			this.age = age;
		}else{
			this.age=18;
		}
		
		
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		if(sex.equals("女")){
		this.sex = "女";
		}else {
			this.sex = "男";
		}
	}
	public department getDepart() {
		return depart;
	}
	public void setDepart(department depart) {
		this.depart = depart;
	}
	public String getDu() {
		return du;
	}
	public void setDu(String du) {
		this.du = du;
	}
	/*
	 * 员工自我介绍信息
	 */
	public String intro(){
		String str="姓名："+this.getStaffname()+"\n工号："
	    +this.getStaffnum()+"\n性别："+this.getSex()+"\n年龄："+this.getAge()+"\n职务："+this.getDu();
		return str;
	}
}


package com.office.test;
import com.office.info.staff;
import com.office.info.duty;
/*
 * 创建测试类
 */
public class officetest {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		duty du1=new duty("001","经理");
		
		staff st1=new staff("张铭","S001","男",29,du1.getDutyname());
		System.out.println(st1.intro());
	}

}