Question

(To be written in Java code)

A personal phone directory contains room for first names and phone numbers for 30 people. Assign names and phone numbers for the first 10 people. Prompt the user for a name, and if the name is found in the list, display the corresponding phone number. If the name is not found in the list, prompt the user for a phone number, and add the new name and phone number to the list.

Continue to prompt the user for names until the user enters quit. After the arrays are full (containing 30 names), do not allow the user to add new entries.

Use the following names and phone numbers:

Name	Phone #
Gina	(847) 341-0912
Marcia	(847) 341-2392
Rita	(847) 354-0654
Jennifer	(414) 234-0912
Fred	(414) 435-6567
Neil	(608) 123-0904
Judy	(608) 435-0434
Arlene	(608) 123-0312
LaWanda	(920) 787-9813
Deepak	(930) 412-0991

This code was provided to start with:

import java.util.*;
class PhoneNumbers
{

public static void main (String[] args)

{

// write code here

}

}

Answer 1

the above problem can be divided into following steps :

1. create a global map and count variable .
2. create a function to add the user . asks for username and phone number , check if count < 30 and add if the yes.
3. create a function to check if user is present in the phone book . take string name as parameter , check if the map contains the name , if yes then print the name and number , else , ask for number and add the user name and number if count < 30 and increment the count.

more details in the code .

text code :

import java.util.*;

public class Main{
public static Map<String , Integer> phone_list = new HashMap<String , Integer>(); //global map to store the name and its number
static int count = 0; //count to keep track of number of users.
  
public static void check_user(String user){ //function to check if user is there
Scanner in = new Scanner(System.in);
if(phone_list.containsKey(user)){
System.out.println("Entry found");
System.out.println(user + " : " + phone_list.get(user));
}
else{
if(count >= 30){
System.out.println("Sorry! , the phone book can have only 30 contacts in it.");
System.exit(0);
}
System.out.println("User not found in the entry , please enter a phone number for this user");
int p_no = in.nextInt();
phone_list.put(user , p_no);
count ++;
System.out.println("user addedin the phone book");
}
}
  
public static void add_user(){ //fucntion to add the user
Scanner in = new Scanner(System.in);
if(count >= 30){
System.out.println("Sorry! , the phone book can have only 30 contacts in it.");
System.exit(0);
}
System.out.println("user name : ");
String name = in.nextLine();
System.out.println("Phone no");
int p_no = in.nextInt();
phone_list.put(name , p_no);
count ++;
System.out.println("user addedin the phone book");
}
  

public static void main (String[] args){
Scanner in = new Scanner(System.in);
add_user();
add_user();
System.out.println("DO you want to add more users: ");
String choice = in.nextLine();
while(!choice.equals("quit")){
add_user();
System.out.println("DO you want to add more users: ");
choice = in.nextLine();
}
System.out.println("Enter the string to search in the phone_book ");
String s = in.nextLine();
check_user(s);
}
}