1 回答if(students.containsValue(new Student(null,name))) {

5 回答studentList.add(new Student(random.nextInt(1000),"Mike"));這行代碼出問(wèn)題了，提示不能從Student的<String,String>轉(zhuǎn)換成<int,String>

2 回答this.students = new HashMap<String,Student>(); 這句該怎么理解？

3 回答containsValue(new Student(null,name)中為什么Student的ID對(duì)應(yīng)值是空（null）呢

2 回答為什么聲明public Map<String,Student> students之后不直接=new HashMap<String,Student>() 而是在構(gòu)造函數(shù)中