Import? Java . io . *；
Class? StuMgr{
Public? Static electricity Class? Students {
Public? int？ id；
Public? String? Name;
Public? int？ Age;
Public? Student (int? id？ , string? Name, int? Age) (
This. id? =? id；
This name? =? Name;
This. Age? =? Age;
}
@ Overlay
Public? String? toString(){
Return? id？ +? ","? +? Name? +? ","? +? Age;
}
}
Public? List & lt students & gt? stuList？ =? New? LinkedList & lt& gt();
Public? Invalid? add(){
Scanner? sc？ =? New? Scanner (system. in); ?
System.out.println ("Please enter your student number:");
String? id？ =? sc . nextline()；
int？ intId？ =? 0;
Try {
intId？ =? integer . parse int(id)；
}catch(NumberFormatException？ For example) {
System.out.println ("The student number is entered incorrectly, please enter a number!" );
Return;
}
What if? (find(intId)？ ! =? null){
System.out.println ("This student number already exists!" );
Return? ;
}
System.out.println ("Please enter student name:");
String? Name? =? sc . nextline()；
System.out.println ("Please enter student age:");
String? Age? =? sc . nextline()；
int？ intAge？ =? 0;
Try {
intAge？ =? Integer.parseInt (age);
}catch(NumberFormatException？ For example) {
System.out.println ("Age input is wrong, please enter a number!" );
Return;
}
Student? Stu? =? New? Student (intId, name, intage);
stu list . add(stu)；
store()；
system . out . println("-")；
System.out.println ("student information has been increased");
system . out . println(stu)；
system . out . println("-")；
}
Public? Invalid? del(){
Scanner? sc？ =? New? Scanner (system. in); ?
System.out.println ("Please enter your student number:");
String? id？ =? sc . nextline()；
int？ intId？ =? 0;
Try {
intId？ =? integer . parse int(id)；
}catch(NumberFormatException？ For example) {
System.out.println ("The student number is entered incorrectly, please enter a number!" );
Return;
}
Student? Stu? =? find(intId)；
What if? (? Stu? ==? null){
System.out.println ("This student number does not exist!" );
Return? ;
}
stu list . remove(stu)；
store()；
system . out . println("-")；
System.out.println ("student information has been deleted");
system . out . println(stu)；
system . out . println("-")；
}
Public? Invalid? find(){
Scanner? sc？ =? New? Scanner (system. in); ?
System.out.println ("Please enter your student number:");
String? id？ =? sc . nextline()；
int？ intId？ =? 0;
Try {
intId？ =? integer . parse int(id)；
}catch(NumberFormatException？ For example) {
System.out.println ("The student number is entered incorrectly, please enter a number!" );
Return;
}
Student? Stu? =? find(intId)；
What if? (? Stu? ==? null){
System.out.println ("This student number does not exist!" );
Return? ;
}
system . out . println("-")；
System.out.println ("Find student information as follows");
system . out . println(stu)；
system . out . println("-")；
}
Public? Student? find(int？ id){
For (students? Stu? :? stuList){
If (stu.id? ==? id){
Return? Stu;
}
}
Return? null
}
Public? Invalid? modify(){
store()；
}
Public? Invalid? foreach(){
system . out . println("-")；
For (students? Stu? :? stuList){
system . out . println(stu)；
}
system . out . println("-")；
}
Public? Invalid? store(){
Iterator? Iterator? =? stu list . iterator()；
Documents? Documents? =? New? file(" stu list . txt ")；
FileWriter？ fw？ =? null
BufferedWriter？ A writer? =? null
Try it? {
fw？ =? New? FileWriter (file)
A writer? =? New? buffered writer(fw)；
while(iterator.hasNext()){
writer.write(iterator.next()。 toString())；
writer . newline()； //newline
}
writer . flush()；
}? Catch? (FileNotFoundException？ e)？ {
e . printstacktrace()；
} catch? (IOException？ e)？ {
e . printstacktrace()；
} Finally {
Try it? {
writer . close()；
fw . close()；
}? Catch? (IOException？ e)？ {
e . printstacktrace()；
}
}
}
Public? Static electricity Invalid? main(String[]？ args){
StuMgr？ Manager? =? New? stu mgr()；
while(true){
System.out.println ("Please select the operation to be performed:");
System.out.println(" 1: add student information ");
System.out.println("2: delete student information ");
System.out.println("3: find student information ");
System.out.println("4: modify student information ");
System.out.println("5: traverse student information ");
system . out . println(" 6:exit ")；
system . out . println("-")；
Scanner? sc？ =? New? Scanner (system. in); ?
String? op？ =? sc . nextline()；
if("6 "。 Equal to (op)){) (
Return;
}
if(" 1 "。 Equal to (op)){) (
mgr . add()；
}
if("2 "。 Equal to (op)){) (
mgr . del()；
}
if("3 "。 Equal to (op)){) (
mgr . find()；
}
if("4 "。 Equal to (op)){) (
mgr . modify()；
}
if("5 "。 Equal to (op)){) (
mgr . foreach()；
}
}
}
Time is pressing, and there is still a modify method that has not been implemented, leaving it to everyone to practice.