How do I make a method that will make it so the list of contacts in my program are sorted by their phone numbers?

Here's my code so far:

import java.io.*;

import java.util.*;

class Entry {

public String name, number, note;

}

public class PBN {

public static Entry[] contactList;

public static int num_entries;

public static Scanner stdin = new Scanner(System.in);

public static void main(String args[]) throws Exception{

int i; char C;

String code, Command;

contactList = new Entry[200];

num_entries = 0;

try {

readPhoneBook("phonebook.txt");

} catch (FileNotFoundException e) {

}

System.out.println("Codes are entered as 1 to 8 characters. Use" +

" \"e\" for enter," +

" \"f\" for find," +

" \"l\" for listing all the entries," +

" \"q\" to quit.");

Command = null;

C = ' ';

while(C != 'q'){

System.out.print("Command: ");

Command = stdin.next();

C = Command.charAt(0);

switch (C) {

case 'e': addContact(); break;

case 'f':

code = stdin.next();

stdin.nextLine();

i = index(code);

if (i >= 0) displayContact(contactList[i]);

else System.out.println("**No entry with code " + code); break;

case 'l':

listAllContacts(); break;

case 'q':

CopyPhoneBookToFile("PhoneBook1.txt");

System.out.println("Quitting the application. All the entries are "

+ "stored in the file PhoneBook1.txt"); break;

case 'a':

sortList(); break;

case 'm':

default:

System.out.println("Invalid command Please enter the command again!!!");

}

}

}

public static void readPhoneBook(String FileName) throws Exception {

File F;

F = new File(FileName);

Scanner S = new Scanner(F);

while (S.hasNextLine()) {

contactList[num_entries]= new Entry();

contactList[num_entries].name = S.next();

contactList[num_entries].number = S.next();

contactList[num_entries].note = S.nextLine();

num_entries++;

}

S.close();

}

public static void addContact() {

String name = stdin.next();

String number;

stdin.nextLine();

String pattern = "^\\(?(\\d{3})?\\)?[- ]?(\\d{3})[- ](\\d{4})$";

contactList[num_entries] = new Entry();

contactList[num_entries].name = name;

System.out.print("Enter Number: ");

number = stdin.nextLine();

if (number.matches(pattern)) {

contactList[num_entries].number = number;

} else {

System.out.println("Error!");

System.out.println("Not proper digit format! Use \"012-3456\", \"(012)345-6789\"" +

", or \"012-345-6789\" format.");

System.out.print("Enter number: ");

number = stdin.nextLine();

}

System.out.print("Enter Notes: ");

contactList[num_entries].note = stdin.nextLine();

num_entries++;

System.out.println(" ");

}

public static int index(String Key) {

// Function to get the index of a key from an array

// if not found, returns -1

for (int i=0; i < num_entries; i++) {

if (contactList[i].name.equalsIgnoreCase(Key))

return i; // Found the Key, return index.

}

return -1;

}

public static void displayContact(Entry contact) {

System.out.println("--"+ contact.name+"\t");

System.out.println("--"+ contact.number+"\t");

System.out.println("--"+ contact.note);

System.out.println("");

}

public static void listAllContacts() {

int i = 0;

while (i < num_entries) {

displayContact(contactList[i]);

i++;

}

}

public static void sortList() {

int i;

Entry temp;

temp = new Entry();

for (int j = 0; j< num_entries; j++) {

for (i = j + 1; i < num_entries; i++) {

if (contactList[j].name.compareToIgnoreCase(contactList[i].name)> 0) {

temp = contactList[j];

contactList[j] = contactList[i];

contactList[i] = temp;

}

}

}

}

public static void CopyPhoneBookToFile(String FileName) throws Exception{

FileOutputStream out = new FileOutputStream(FileName);

PrintStream P = new PrintStream( out );

for (int i=0; i < num_entries; i++) {

P.println(contactList[i].name + "\t" + contactList[i].number +"\t" + contactList[i].note);

}

}

}