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Question about the task

Phone number verification

Java Multithreading, Level 2, Lesson 13

Under discussion

Sorry the code is a bit messy; not sure why it isn't working

The checkPhoneNumber method should check whether the phoneNumber argument is a valid phone number.

Verification criteria:
1) if the number starts with '+', then it must contain 12 digits
2) if the number starts with a digit or opening parenthesis, then it must contain 10 digits
3) the number may contain 0-2 non-consecutive '-' characters
4) the number may contain 1 pair of matching parentheses, which must be to the left of the '-' characters
5) the parentheses must contain exactly 3 digits
6) the number cannot contain letters
7) the number must end with a digit

Here are some examples:

+380501234567 - true
+38(050)1234567 - true
+38050123-45-67 - true
050123-4567 - true
+38)050(1234567 - false
+38(050)1-23-45-6-7 - false
050xxx4567 - false
050123456 - false
(0)501234567 - false

Requirements:

The checkPhoneNumber method should return a boolean.
The checkPhoneNumber method must be public.
The checkPhoneNumber method must have one String parameter.
The checkPhoneNumber method must correctly check the validity of the phone number passed as an argument.

package com.codegym.task.task22.task2212; /* Phone number verification */ import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; public class Solution { public static boolean checkPhoneNumber(String phoneNumber) { String[] digits = phoneNumber.split(""); int numbers = 0; boolean startsPlus = false; int dashes = 0; int brackets = 0; for (int i = 0; i < digits.length; i++){ if (i == 0) if (digits[i].equals("+")){ startsPlus = true; continue; } if (isNumeric(digits[i])) numbers++; else if (digits[i].equals("-")){ if (i == digits.length-1 || digits[i+1].equals("-")) return false; dashes++; } else if (digits[i].equals("(")){ if (dashes>0 || i > digits.length-5 || !digits[i+3].equals(")")) return false; brackets++; } else if (digits[i].equals(")")) if (dashes>0 && brackets!=1) return false; else return false; } if (startsPlus) if (numbers != 12) return false; else if (numbers != 10) return false; return dashes <= 2 && brackets <= 1; } public static boolean isNumeric(String str) { try { Double.parseDouble(str); return true; } catch(NumberFormatException e){ return false; } } public static void main(String[] args) throws IOException { BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in)); String s = bufferedReader.readLine(); boolean phoneNumber = checkPhoneNumber(s); System.out.println(phoneNumber); } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

6 February 2021, 22:46

I don't know what is wrong yet, but i have some tips to simplify and make your code more efficient: #1 check what the first digit is outside the loop and start the loop with i being at 1. There will only be one cycle where i equals 0, and considering it will be the least likely occurrence, checking for it every cycle is very inefficient. Also, if the string doesn't start with a plus sign, parentheses, or a number then you know the answer is already false and don't need the loop. #2 before the loop starts, check that the string ends with a number. You don't need to move any further if this is false as you would know the answer to the problem is false #3 Don't ever use the Exception system to solve a problem like that. It was not designed to do that and doing so is highly inefficient. The purpose is to ensure is to solve problems you don't know, as a way of tracing where the problems originate. In this case It would be like using a 5lb sledge hammer to hammer in regular 3" nails. Does it get the job done? Yes. Will you be able to do it all day? Not unless you are Hercules. In the case that you are using it for in this code using Character.isDigit() would be quite a bit more appropriate. This task is also made to be completed with regex statements. I highly recommend that you do a little research on them and apply them to this task. Here is a link to a place you can start: Regular Expressions