main 方法测试 TeacherService 的 addTeacher 方法，

这个就是简单的类和对象加个单例模式，如需进一步协助可以私信

package service;

import java.util.HashMap;

public class TeacherService {
	class Teacher{
		String name;
		String major;
	}
	private static TeacherService ts=null;
	HashMap<String, Teacher> hm=new HashMap<String, Teacher>();
	
	public static TeacherService getInstanse(){
		if(ts==null){
			ts=new TeacherService();
		}
		return ts;
	}
	
	public TeacherService(){
		
	}
	
	public TeacherService(HashMap<String, Teacher> hm){
		this.hm=hm;
	}
	
	public void addTeacher(String name,String major){
		Teacher t = new Teacher();
		t.name=name;
		t.major=major;
		this.hm.put(name, t);
				
	}
	
	public Teacher findTeacher(String name){
		Teacher t = hm.get(name);
		return t;
	}
	
	public static void main(String[] args) {
		TeacherService ts = new TeacherService();
		
		ts.addTeacher("张三", "教授");
		ts.addTeacher("李四", "主任");
		
		Teacher t = ts.findTeacher("张三");
		System.out.println("查找："+t.name+" , "+t.major);
	}
	
}