CODEWITHSUNDEEP
java
user7911687
user7911687

Reputation:

Java Entry Validation

I'm working on a server/client battleship game using sockets. Part of the project requires entry validation on the client side for entering tile locations. A user is supposed to enter a letter A-E and a number 1-5, and right now if you type in something invalid, it seems to freeze. Any help would be much appreciated, thanks in advance!

            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);

Upvotes: 0

Views: 35

Answers (2)

ΦXocę 웃 Пepeúpa ツ
ΦXocę 웃 Пepeúpa ツ

Reputation: 48258

My suggestion on the other hand will suggest to implement regex with a pattern that allows you to match 1st char alpha(no matter capitalization) followed by a number, both in a range from a → e and 1 → 5

    Scanner sc = new Scanner(System.in);

    System.out.println("Please type in a ....y number, such as 'A1'. ");

    do {
        inp = sc.nextLine();
        if (inp.matches("^[a-eA-E1-5]{0,2}")) {
            inpArr[k++] = inp;

        } else {
            System.out.println("invalid input");
        }
    } while (k < numberOfElements);

    System.out.println(Arrays.toString(inpArr));

Upvotes: 0

Elliott Frisch
Elliott Frisch

Reputation: 201429

I would suggest you test each character separately by breaking them out with charAt, and please respect variable naming conventions. Something like

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'));
}

Upvotes: 1

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