第六章第二十一题（电话按键盘）(Phone keypads) - 编程练习题答案

*6.21（电话按键盘）国际标准的字母/数字匹配图如编程练习题4.15所示，编写一个方法，返回给定大写字母的数字，如下所示：

int getNumber(char uppercaseLetter)

编写一个测试程序，提示用户输入字符串形式的电话号码。输入的数字可能会包含字母。程序将字母（大写或者小写）翻译成一个数字，然后保持其他字符不变。

*6.21(Phone keypads)The international standard letter/number mapping for telephones is given in Programming Exercise 4.15. Write a method that returns a number, given an uppercase letter, as follows:

int getNumber(char uppercaseLetter)

Write a test program that prompts the user to enter a phone number as a string. The input number may contain letters. The program translates a letter (uppercase or lowercase) to a digit and leaves all other characters intact.

下面是参考答案代码:

// https://cn.fankuiba.com

import java.util.Scanner;

public class Ans6_21_page201 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String phoneNumber = input.nextLine().toUpperCase();
        for (int i =0; i < phoneNumber.length(); i++) {
            if (Character.isDigit(phoneNumber.charAt(i))) {
                System.out.print(phoneNumber.charAt(i));
            }
            else if (getNumber(phoneNumber.charAt(i)) == 1)
                System.out.print("-");
            else
                System.out.print(getNumber(phoneNumber.charAt(i)));
        }
    }
    public static int getNumber(char uppercaseLetter) {
        int num = 99;
        switch (uppercaseLetter+"") {
            case "-":
                num = 1;
                break;
            case "A":
                num = 2;
                break;
            case "B":
                num = 2;
                break;
            case "C":
                num = 2;
                break;
            case "D":
                num = 3;
                break;
            case "E":
                num = 3;
                break;
            case "F":
                num = 3;
                break;
            case "G":
                num = 4;
                break;
            case "H":
                num = 4;
                break;
            case "I":
                num = 4;
                break;
            case "J":
                num = 5;
                break;
            case "K":
                num = 5;
                break;
            case "L":
                num = 5;
                break;
            case "M":
                num = 6;
                break;
            case "N":
                num = 6;
                break;
            case "O":
                num = 6;
                break;
            case "P":
                num = 7;
                break;
            case "Q":
                num = 7;
                break;
            case "R":
                num = 7;
                break;
            case "S":
                num = 7;
                break;
            case "T":
                num = 8;
                break;
            case "U":
                num = 8;
                break;
            case "V":
                num = 8;
                break;
            case "W":
                num = 9;
                break;
            case "X":
                num = 9;
                break;
            case "Y":
                num = 9;
                break;
            case "Z":
                num = 9;
        }
        return num;
    }
}

适用Java语言程序设计与数据结构（基础篇）（原书第11版）Java语言程序设计（基础篇）（原书第10/11版） 更多内容