Java - 在do while中使用逻辑OR

Question

I'm fairly new at this programming, so please do bear with me.

In teaching myself I'm attempting to write a Batteleships game; not OO at the moment, but rather procedural - little steps at a time.

I have a method to read the coordinates to fire at, these coordinates I want to then validate to make sure that, well, they're valid. There is one method that checks that they are numbers and within the correct range, the other method is 'supposed' to check through what has already been entered.

The issue I'm finding is that I'm not breaking out of the do while loop to progress, the while bit is using logical OR on the two aforementioned methods. In writing these methods, they both do what they're supposed to do, well I'm not entirely sure about the method that checks whether a coordinate has already been fired at.

Some pointers would be really appreciated (on any aspect of it), thanks!

Code:

public static String inputCoords(List<String> coordsFired){
    Scanner sc = new Scanner(System.in);

    //Console c = System.console();
    String coordsEntered;

    do {
        System.out.println("in do\\while");
        System.out.println("Enter coordinates as 'x, y': ");
        coordsEntered = sc.nextLine();
        System.out.println("end of do\\while loop");
    } while(!validateCoords(coordsEntered) 
         || !coordsFiredAt(coordsEntered, coordsFired));

    coordsFired.add(coordsEntered);
    System.out.println("contents of List<String> coordsFired" + coordsFired);

    return coordsEntered;
}

public static boolean validateCoords(String coordsEntered){
    boolean results;
    int x, y;
    String strx = splitCoordsString(coordsEntered, 'x');
    String stry = splitCoordsString(coordsEntered, 'y');

    if (numericCheckCoordsFire(strx) && numericCheckCoordsFire(stry)) {
        x = Integer.parseInt(strx);
        y = Integer.parseInt(stry);

        if (x > 25 || y > 25) {
            results = false;
            System.out.println("The dimensions of the board are 25 x 25, 'x,y' entered must be less than this.  You entered '" + strx + "' for x and '" + stry + "' for y.");
        } else {
            results = true;
        }
    } else {
        results = false;
        System.out.println("Coords are supposed to be numbers...  You entered '" + strx + "' for x and '" + stry + "' for y.");
    }

    System.out.println(results);
    return results;
}

public static boolean coordsFiredAt(String coordsEntered, List<String> coordsFired) {
    boolean results = false;

    // go through each item in the list and compare against coordsEntered
    for (String s : coordsFired) {
        System.out.println("in for loop, printing iterated var" + s);

        if (s.equals(coordsEntered)) {
            // put these matched coordsFire into listHit
            results = false;
        } else {
            System.out.println("already fired at " + coordsEntered);
            results = true;
        }
    }

    return results;
}

Answer 1

I propose you add OOP a little and create a class for Coords:

public class Coords {

    private final int x;
    private final int y;

    public Coords(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public int getX() {
        return x;
    }

    public int getY() {
        return y;
    }

    /**
     * This method is used for Coords comparison
     */
    @Override
    public boolean equals(Object o) {
        Coords coords = (Coords) o;
        return y == coords.y && coords.x ==x;
    }

    /**
     * This method is used to output coords.
     */
    @Override
    public String toString() {
        return "(" + x + "," + y + ")";
    }
}

So you code will look somethink like this:

public static Coords inputCoords(List<Coords> coordsFired) {
        Scanner sc = new Scanner(System.in);

        //Console c = System.console();
        Coords coords;

        do {
            System.out.println("in do\\while");
            System.out.println("Enter coordinates as 'x, y': ");
            String coordsEntered = sc.nextLine();
            coords = parseCoords(coordsEntered);
            System.out.println("end of do\\while loop");
        } while (coords == null || !areCoordsValid(coords) || !areCoordsNotFired(coords, coordsFired));

        coordsFired.add(coords);
        System.out.println("contents of List<String> coordsFired" + coordsFired);

        return coords;
    }

    public static boolean areCoordsValid(Coords coords) {
        boolean result = true;

        if (coords.getX() > 25 || coords.getY() > 25) { // I think you also need to validate that it is possible values
            result = false;
            System.out.println("The dimensions of the board are 25 x 25, 'x,y' entered must be less than this. " +
                    "You entered '" + coords.getX() + "' for x and '" + coords.getY() + "' for y.");
        }

        return result;
    }

    public static boolean areCoordsNotFired(Coords coords, List<Coords> firedCoards) {
        boolean result = true;
        if (firedCoards.contains(coords)) {
            result = false;
            System.out.println("You already fired at " + coords.getX() + "," + coords.getY());
        }
        return result;
    }

    public static Coords parseCoords(String coordsEntered) {
        Coords coords = null;
        try {
            String[] splittedCoords = coordsEntered.split(","); // Method splits values by comma. It should return an array of Strings with x value at the first element and y at the second one;
            if (splittedCoords.length == 2) {
                String x = splittedCoords[0].trim(); // Method removes all spaces at the beginning and ending of a passed String
                String y = splittedCoords[1].trim();
                coords = new Coords(Integer.parseInt(x), Integer.parseInt(y)); //Creates new instance of Coords class. x and y are passed as constructor params.
            } else {
                System.out.println("Format for coords is wrong.  You entered '" + coordsEntered + "'.");
            }

        } catch (NumberFormatException e) { // Integer.parseInt throws an exception if the string does not contain parsable integer.
            // We catch an exception and handle it by writing a message
            System.out.println("Coords are supposed to be numbers...  You entered '" + coordsEntered + "'.");
        }
        return coords;
    }

Also Set is more applicable in this case. Set contains no duplicate elements and Set.contains() method works faster then List.contains() . But if you want to use Set you should implement both equals() and hashCode() methods.

Answer 2

You want to loop if the coords are invalid or already fired.

So shouldn't the while condition be:

while(!validateCoords(coordsEntered) 
     || coordsFiredAt(coordsEntered, coordsFired))