Week 3: Objects, files and exceptions/22. Phone book 4: Menu

Write the method

public static void start()

which initialises the HashMap object needed in the phone book and prints a menu, 
where the user can choose which operation to perform.


The program then calls either the method 
- addNumber,
- findNumber or
- listBook. 
It is not necessary to define the methods, it is sufficient to call them. 
All methods get a HashMap object as a parameter.



An example of program execution:
1. Add number
2. Find number
3. List numbers
0. Exit
Option: 1
Name: Pete
Number: 12345

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 1
Name: Jack
Number: 54321

1. Add number
2. Find number
3. List numbers
0. Exit
Choice: 3
Name: Jack, number: 54321
Name: Pete, number: 12345

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 2
Name: Pete
Number: 12345

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 0






================================================



import java.util.Random;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Collections;
import java.util.ArrayList;
import java.util.Scanner;



public class Test{
    public static void main(String[] args){
        final Random r = new Random();
        
        // <hide>
        
        String[] s = {"1","Pete","12345","1","Jack","54321", "1", "Maya", "99999", "3", "2", "Pete", "2", "Jack", "0"};
        Scanner.setStream(s);
        start();
        
        
        
    }
    


    //q22
    public static void start() {
        HashMap<String, String> numbers = new HashMap<>();
        Scanner reader = new Scanner(System.in);
        
        while (true) {
            // Options Menu
            System.out.println("1. Add number");
            System.out.println("2. Find number");
            System.out.println("3. List numbers");
            System.out.println("0. Exit");

            // User inputs what 'option' they want
            System.out.print("Option: ");
            int option = Integer.parseInt(reader.nextLine());

            // Exit if option is 0
            if (option == 0) {
                break;
            }
            // Add Number if option is 1
            else if (option == 1) {
                addNumber(numbers);
            }
            else if (option == 2) {
                findNumber(numbers);
            }
            else if (option == 3) {
                listBook(numbers);
            }
            // if none of the options exist - continue. no printouts
            else {
                continue;
            }

            // print 1 extra line separating subsequent option selections
            System.out.println("");
        }
    }





    
}










1. Add number
2. Find number
3. List numbers
0. Exit
Option: 1
Name: Pete
Number: 12345

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 1
Name: Jack
Number: 54321

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 1
Name: Maya
Number: 99999

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 3
Name: Jack, number: 54321
Name: Maya, number: 99999
Name: Pete, number: 12345

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 2
Name: Pete
Number: 12345

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 2
Name: Jack
Number: 54321

1. Add number
2. Find number
3. List numbers
0. Exit
Option: 0