在Java中从arrayList筛选字符串

Question

我有一个包含学生成绩的ArrayList，我想用给定的成绩字母筛选学生。例如，如果用户输入A，表格必须显示所有成绩为F的学生。但问题是它没有过滤它

  static List<Assign2> studentList = new ArrayList<>();


    String letter = JOptionPane.showInputDialog(this,"Which grade do you want to filter?");

            List<Assign2> remaining = new ArrayList<>(studentList);
            for(int i=0;i<remaining.size();i++){
                if(remaining.get(i).getLetterGrade()!=letter){

                    remaining.remove(i);
                }
            }

            table(remaining);