Question

import java.util.Scanner;
public class phonenumberformat {

    public static void main(String [] args) {

        //Create the scanner class for user input
        Scanner keyboard = new Scanner(System.in);

        System.out.println("Please enter your phone number: ");
        String number = keyboard.next();

        /* Separate the number into the three categories I want
         * Side-Note: Since we can assume that the phone number will be 10 digits long I don't
         *      have to figure out the length of the number that the user will input
         */
        String area_code = number.substring(0,3);
        String first_three = number.substring(3,6);
        String rest = number.substring(6,10);



        int new_number = Integer.parseInt(number);
        if (new_number < 10){
            System.out.println("It seems that you have entered an invalid phone number, please try again!");
            /* I want to make a loop here so that if the user accidentally enters more of less than 
             *      a 10 digit number it will loop the "Please enter your phone number: " part so 
             *      Java won't give an error
             */
        } else {
            //Concatenate the number properly so that it is formatted nicely
            String formatted_number = "(" + area_code + ")" + " " + first_three + "-" + rest;
        }

        String final_number = Integer.toString(formatted_number);

        //Print the newly formatted number
        System.out.println(formatted_number);
    }    
}

所以这个程序应该格式化电话号码从1112223333到（111）222-3333。作业说我们可以假设用户将输入一个未格式化的电话号码，但是我想稍微安全一点，这样如果用户通过改变输入的数字不是10位数而不是错误它将提示他们重新输入号码。谢谢！

Answer 1

使用正则表达式：

String formatted = input.replaceAll("^(\\d{3})(\\d{3})(\\d{4})$", "($1) $2-$3");

这不仅是一个单线解决方案，它不会格式化已经格式化的数字（特别是如果输入不是11位数，则不会发生变化）。

如果您想强制格式替换已存在的格式，那么仍只有一行，只需删除所有非数字：

String formatted = input.replaceAll("\\D", "").replaceAll("^(\\d{3})(\\d{3})(\\d{4})$", "($1) $2-$3");

Answer 2

我已经纠正了你的代码，其中有很多错误你已经应用了Integer.toString（“string Variable”）你可以直接将String赋给String变量

// String rest = number.substring（6,10）;它可以给你StringOutOfBoundException

试试这个

public static void main(String[] args) {
                //Create the scanner class for user input
                Scanner keyboard = new Scanner(System.in);

                System.out.println("Please enter your phone number: ");
                String number = keyboard.next();

                /* Separate the number into the three categories I want
                 * Side-Note: Since we can assume that the phone number will be 10 digits long I don't
                 *      have to figure out the length of the number that the user will input
                 */
                String area_code = number.substring(0,3);
                String first_three = number.substring(3,6);
                String rest = number.substring(6,9);
                String formatted_number ="";

                /* I want to make a loop here so that if the user accidentally enters more of less than 
                 *      a 10 digit number it will loop the "Please enter your phone number: " part so 
                 *      Java won't give an error
                 */

                int new_number = Integer.parseInt(number);
                if (new_number < 10){
                    System.out.println("It seems that you have entered an invalid phone number, please try again!");
                } else {
                    //Concatenate the number properly so that it is formatted nicely
                    formatted_number = "(" + area_code + ")" + " " + first_three + "-" + rest;
                }

                String final_number = formatted_number;

                //Print the newly formatted number
                System.out.println(formatted_number);
            }

并且如果您希望用户重新输入该号码以防他出错，那么您必须使用Pattern类来检查它是否有效

Answer 3

这应该有效：

import java.util.Scanner;
public class phonenumberformat {

    public static void main(String [] args) {

        //Create the scanner class for user input
        Scanner keyboard = new Scanner(System.in);

        boolean notValid = true;

        System.out.println("Please enter your phone number: ");

        while(notValid)
        {
            String number = keyboard.next();

            if (number.length() !=10){
                System.out.println("It seems that you have entered an invalid phone number, please try again!");

            } else {
                String area_code = number.substring(0,3);
                String first_three = number.substring(3,6);
                String rest = number.substring(6,10);

                //Concatenate the number properly so that it is formatted nicely
                String formatted_number = "(" + area_code + ")" + " " + first_three + "-" + rest;
                //Print the newly formatted number
                System.out.println(formatted_number);

                notValid = false;
            }

        }
    }    
}

我需要帮助在Java中的if-else语句中创建循环

3 个答案: