如何使我的Java程序包含大写和小写字符？

Question

我正在尝试在代码中包含可用字符的大写和小写字母，但是我不确定该如何处理。 谁能给我一些见识？

以下是到目前为止我编写的代码：

import java.util.Scanner;

public class ShopSign {

public static void main(String[] args) {
    // Scanner class//
    Scanner input = new Scanner(System.in);
    // variable to store available characters//
    String availableCharacters;     
    // variable to store proposed message//
    String proposedMessage;
    // variable to keep track if message will make it or not to the sign board//
    boolean flag = true;
    // variable to store the character that remain short//
    char shortCharacter = ' ';
    // variable to store character at current position//
    char temp;                      

    // Prompt for input of available characters//
    System.out.println("Enter available characters:");
    // read available characters
    availableCharacters = input.nextLine();

    // Prompt for input of proposed message//
    System.out.print("Enter proposed message: ");
    // read proposed message//
    proposedMessage = input.nextLine();


    // remove white spaces from the message//
    proposedMessage = proposedMessage.replaceAll("\\s","");

    //check if character it is available//
    for(int i = 0; i < proposedMessage.length(); i++){
        temp = proposedMessage.charAt(i);

        // if character is not the whitespace//
        if(temp != ' '){
            // check if character is available//
            if(availableCharacters.indexOf(temp) >= 0){
                // replace the character to empty string from available characters//
                availableCharacters = availableCharacters.replaceFirst(Character.toString(temp), "");
            }
            // otherwise mark the flag false and break the loop//
            else{
                flag = false;
                shortCharacter = temp;
                break;
            }
        }
    }

    // Print the appropriate message to the user//
    if(flag){
        System.out.println("The message makes it to the sign board.");
    }
    else{
        System.out.println("We are short of character "+ Character.toString(shortCharacter) +".");
        }
    input.close();
    }
}

Answer 1

您到底想做什么？ 在使用您的代码并使用aAbB作为可用字母之后，我随后输入AaBb作为建议的消息，并输出“ This message makes it to the sign board. ”

编辑; 如果您只允许使用任何一个字符（大写和小写），则可以执行以下操作：

availableCharacters = availableCharacters.replaceFirst(Character.toString(temp).toLowerCase(), "");
availableCharacters = availableCharacters.replaceFirst(Character.toString(temp).toUpperCase(), "");

Answer 2

您的期望不清楚，但是我对您的代码有建议：

1. 不需要检查if(temp != ' ')因为您已经在前面的代码中清除了空格字符：

   proposalMessage = proposalMessage.replaceAll（“ \\ s”，“”）;

2. 如果proposalMessage包含特殊字符，则您的代码将失败（示例：+ \\ ...）

   在使用replaceFirst之前需要使用Pattern.quote：

    String pattern = Pattern.quote(Character.toString(temp)); availableCharacters = availableCharacters .replaceFirst(pattern, "");