java - Why is that when I search and write the desired index, it displays all the student list? -

this code. after adding 2 or more students in list , press search , desired index, shows student list need 1 output not students i've input.

    studentserviceimpl studservimpl = new studentserviceimpl();       scanner scan = new scanner(system.in);       do{      system.out.print("select number: ");     system.out.println();     number=scan.nextint();      list<student> studentlist = new arraylist<student>(); 

this add multiple student list

if(number==1){          student student =  new student();            system.out.println("enter student no.");         studid = scan.next();          student.setstudid(studid);            system.out.println("enter first name:");         firstname = scan.next();          student.setfirstname(firstname);            system.out.println("enter last name:");         lastname = scan.next();          student.setlastname(lastname);                studservimpl.add(student);            } 

this search method

    else if(number ==2) {           studentlist = studservimpl.search(index);          system.out.println("enter desired index");         index = scan.nextint();           (student student2 : studentlist) {              system.out.println("student id: "+ student2.getstudid());             system.out.println("firstname: "+student2.getfirstname());             system.out.println("lastname: "+student2.getlastname()+"\n");          }       } 

this exit...

        else if(number == 3){              system.out.println("thank you, bye!");         }            }           while(number!=0);      }     } 

this search method class, studentserviceimpl:

public list<student> search(int index) {          studentlist.get(index);          return studentlist;     }