Java-对list里面的元素进行冒泡排序

public class Student{
privete String studentNo;
private String studentName;
....
}

public List<Students> demo(){
    List<Students> list = new ArrayList<Students>();
    for (int i = 0; i < list .size(); i++)    {  
        for (int j = list .size()-1; j > i; j--)  {  
            String no= list .get(j).getStudentNo();
            String no_1= list .get(j-1).getStudentNo();
            if (no.compareTo(no_1)>0)    {  
                  //互换位置
                 Student  stu = list.get(j);
                 list.set(j, list.get(j-1));
                 list.set(j-1, stu );
            }  
        }  
    } 
    return list
}