Sorting string alphabetically in linked list(Java)

import java.util.*; public class test { public static void main(String [] args) { contacts l=new contacts(); try { Scanner k=new Scanner(System.in); boolean ans=true; do { System.out.println("#ENTER THE NUMBER OF SERVICE\n\t1.New Contact\n\t2.Change Number\n\t3.delete contact\n\t4.Search for contact\n\t5.Print contacts"); int choice = k.nextInt(); switch (choice) { case 1: String name, address,rel; int number; System.out.println("\tEnter name\n\tAnd address\n\tAnd relation\n\tAnd number"); l.newContact(name=k.next(),address=k.next(),rel=k.next(),number=k.nextInt()); break; case 2: System.out.println("Enter your the name ,old number then the new number"); l.changePhone(k.next(),k.nextInt(),k.nextInt()); break; case 3: System.out.println("Enter the name of the contact you want to delete"); l.delete(k.next()); break; case 4: System.out.println("Enter name to search for in contacts"); l.searchByName(k.next()); break; case 5: l.print(); break; default: System.out.println("incorrect input"); } System.out.println("#DO YOU NEED ANOTHER SERVICE? (type true if YES and false if NO)"); ans=k.nextBoolean(); } while(ans==true); } catch(InputMismatchException e) { System.out.println("invalid input value!"); } } }