Java 条目验证

Question

我正在使用套接字开发服务器/客户端战舰游戏。该项目的一部分需要在客户端进行输入验证以输入图 block 位置。用户应该输入字母 A-E 和数字 1-5，现在如果你输入无效的内容，它似乎会卡住。任何帮助将不胜感激，提前致谢!

            do{
            System.out.println("------------------------------------------------------------------------------------------------"); 
            System.out.println("Please type in a board position in the format of a letter followed by number, such as 'A1'. "); 
            Scanner sc = new Scanner(System.in);  
            String BoardChoice = sc.next();  
            if(BoardChoice.equals("A1" ) || BoardChoice.equals("B1" ) || BoardChoice.equals("C1" ) || BoardChoice.equals("D1" ) || BoardChoice.equals("E1" ) || 
               BoardChoice.equals("A2" ) || BoardChoice.equals("B2" ) || BoardChoice.equals("C2" ) || BoardChoice.equals("D2" ) || BoardChoice.equals("E2" ) || 
               BoardChoice.equals("A3" ) || BoardChoice.equals("B3" ) || BoardChoice.equals("C3" ) || BoardChoice.equals("D3" ) || BoardChoice.equals("E3" ) || 
               BoardChoice.equals("A4" ) || BoardChoice.equals("B4" ) || BoardChoice.equals("C4" ) || BoardChoice.equals("D4" ) || BoardChoice.equals("E4" ) || 
               BoardChoice.equals("A5" ) || BoardChoice.equals("B5" ) || BoardChoice.equals("C5" ) || BoardChoice.equals("D5" ) || BoardChoice.equals("E5" ))
            {
                flagtoo = false;
                writer.writeUTF(BoardChoice); 
            }
            else
            {
                System.out.println("Invalid Input Please re-enter!");
            }
            }while(flagtoo);

Answer 1

我建议您使用 charAt 来分别测试每个字符，并且请遵守变量命名约定。类似的东西

boolean valid = false;
String boardChoice = sc.nextLine(); // <-- not next
if (boardChoice.length() == 2) {
    char col = boardChoice.charAt(0);
    char row = boardChoice.charAt(1);
    // The parenthesis here are just for clarity.
    valid = ((col >= 'A' && col <= 'E') && (row >= '1' && row <= '5'));
}