求助，这个应该怎么写

[mengDot]

1、设计一个用户类，该类有编号、姓名、性别属性，另外有一个教师类，继承用户类，教师类里具有属性教龄，方法上课，编写程序实现以上过程，并写出测试代码。(50分)
用户类（User）:
属性：userID、userName、sex
教师类(Teacher):extends User
属性：teachingAge
方法：public String goClass()//学生上课方法
测试类(Test):

//查询所有教师的姓名
public static List getAllUserName(List teachers){
//补全代码
}
//更新给定编号的教师姓名
public static List updateUserById(List teachers，String id){
//补全代码
}

public static void main(String args[]){//部分代码
Teacher user1=new Teacher (*,*,*,*);
Teacher user2=new Teacher (*,*,*,*);
…………
//把用户加到动态数组中，请补全代码

//调用方法getAllUserName( )，请补全代码


//调用方法updateUserById( )，请补全代码

}
}

[mengDot]

求帮助，大哥们

[CixHn]

不明确. //查询所有教师的姓名 for(Teacher teacher:teachers){ System.out.println(teacher.getUserName()); } //更新给定编号的教师姓名 for(int i = 0; i < teachers.size(); i++){ if(id != null && id.equals(teachers.get(i).getId())){ //更新操作 teachers.get(i).setUserName("张老师"); } } //把用户加到动态数组中 CopyOnWriteArrayList<Teacher> teachers = new CopyOnWriteArrayList<>(); teachers.add(对象); teachers.add(对象2); ... //调用方法getAllUserName( ) Teacher.getAllUserName(); // 静态方法 直接类名 //调用方法updateUserById( ) 同上

[qq_39936465]

public class User {
	private String userID,userName,sex;

	/**
	 * @param userID
	 * @param userName
	 * @param sex
	 */
	public User(String userID, String userName, String sex) {
		super();
		this.userID = userID;
		this.userName = userName;
		this.sex = sex;
	}

	public String getUserID() {
		return userID;
	}

	public void setUserID(String userID) {
		this.userID = userID;
	}

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public String getSex() {
		return sex;
	}

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

	@Override
	public String toString() {
		return "User [userID=" + userID + ", userName=" + userName + ", sex=" + sex + "]";
	}
	

}


public class Teacher extends User {
	private String teachingAge;

	/**
	 * @param userID
	 * @param userName
	 * @param sex
	 * @param teachingAge
	 */
	public Teacher(String userID, String userName, String sex, String teachingAge) {
		super(userID, userName, sex);
		this.teachingAge = teachingAge;
	}

	public String getTeachingAge() {
		return teachingAge;
	}

	public void setTeachingAge(String teachingAge) {
		this.teachingAge = teachingAge;
	}
	
	public String goClass() {
		return "Internet";
	}

	@Override
	public String toString() {
		return "{userID=" + getUserID() + ", userName=" + getUserName() + ", sex=" + getSex() +", teachingAge=" + teachingAge+"}" ;
	}

}


import java.util.ArrayList;
import java.util.List;

public class Test {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Teacher user1=new Teacher("1", "zhangsan", "nan", "12");
		Teacher user2=new Teacher("2", "lisi", "nan", "5");
		List<Teacher> list=new ArrayList<Teacher>();
		list.add(user1);
		list.add(user2);
		System.out.println(list);
		System.out.println(getAllUserName(list));
		System.out.println(updateUserById(list, "2"));

	}
	public static List<String> getAllUserName(List<Teacher> teachers) {
		List<String> list=new ArrayList<String>();
		for(Teacher teacher:teachers) {
			list.add(teacher.getUserName());
		}
		return list;
	}
	
	public static List<Teacher> updateUserById(List<Teacher> teachers,String id){
		for(Teacher teacher:teachers) {
			if(teacher.getUserID().equals(id)) {
				teacher.setUserName("wangwu");
			}
		}
		return teachers;
	}

}