Text User Interface for 1024 game

TextUI.java

package game1024.ui;

import game1024.*;

import java.util.ArrayList;
import java.util.Scanner;

/**
 * Created by Hans Dulimarta
 */
public class TextUI {
    private NumberSlider game;
    private int[][] grid;
    private static int CELL_WIDTH;
    private static String NUM_FORMAT, BLANK_FORMAT, RULER;
    private Scanner inp;

    static {
        CELL_WIDTH = 4;
        RULER = "";
        for (int k = 0; k < CELL_WIDTH; k++)
            RULER += "-";
    }

    public TextUI() {
        // TODO: Uncomment the following line and replace XYZ with the name
        // of your class that implements the NumberSlider interface
        //game = new XYZ();

        if (game == null) {
            System.err.println ("*---------------------------------------------*");
            System.err.println ("| You must first modify the UI program.       |");
            System.err.println ("| Look for the first TODO item in TextUI.java |");
            System.err.println ("*---------------------------------------------*");
            System.exit(0xE0);
        }
        game.resizeBoard(4, 6, 64);
        grid = new int[4][6];

        /* Set the string to %4d */
        NUM_FORMAT = String.format("%%%dd|", CELL_WIDTH);

        /* Set the string to %4s, but without using String.format() */
        BLANK_FORMAT = "%" + (CELL_WIDTH) + "s|";
        inp = new Scanner(System.in);
    }

    private void printSeparatorLine(int cols) {
        System.out.printf("+");
        for (int k = 0; k < cols; k++) {
            System.out.print(RULER + "+");
        }
        System.out.println();
    }

    private void renderBoard() {
        /* reset all the 2D array elements to ZERO */
        for (int k = 0; k < grid.length; k++)
            for (int m = 0; m < grid[k].length; m++)
                grid[k][m] = 0;
        /* fill in the 2D array using information for non-empty tiles */
        for (Cell c : game.getNonEmptyTiles())
            grid[c.row][c.column] = c.value;

        /* Print the 2D array using dots and numbers */
        printSeparatorLine(grid[0].length);
        for (int k = 0; k < grid.length; k++) {
            System.out.print("|");
            for (int m = 0; m < grid[k].length; m++)
                if (grid[k][m] == 0)
                    System.out.printf (BLANK_FORMAT, ".");
                else
                    System.out.printf (NUM_FORMAT, grid[k][m]);
            System.out.println();
            printSeparatorLine(grid[k].length);
        }

    }

    /**
     * The main loop for playing a SINGLE game session. Notice that
     * the following method contains NO GAME LOGIC! Its main task is
     * to accept user input and invoke the appropriate methods in the
     * game engine.
     */
    public void playLoop() {
        /* Place the first two random tiles */
        game.placeRandomValue();
        game.placeRandomValue();
        renderBoard();

        /* To keep the right margin within 75 columns, we split the
           following long string literal into two lines
         */
        System.out.print ("Slide direction (W, S, Z, A), " +
                "[U]ndo or [Q]uit? ");
        String resp = inp.next().trim().toUpperCase();
        while (!resp.equals("Q")) {
            switch (resp) {
                case "W": /* Up */
                    game.slide(SlideDirection.UP);
                    renderBoard();
                    break;
                case "S":
                    game.slide(SlideDirection.RIGHT);
                    renderBoard();
                    break;
                case "Z":
                    game.slide(SlideDirection.DOWN);
                    renderBoard();
                    break;
                case "A":
                    game.slide(SlideDirection.LEFT);
                    renderBoard();
                    break;
                case "U":
                    try {
                        game.undo();
                        renderBoard();
                    } catch (IllegalStateException exp) {
                        System.err.println ("Can't undo that far");
                    }
            }
            if (game.getStatus() != GameStatus.IN_PROGRESS)
                break;
            /* To keep the right margin within 75 columns, we split the
                following long string literal into two lines
             */
            System.out.print ("Slide direction (W, S, Z, A), " +
                    "[U]ndo or [Q]uit? ");
            resp = inp.next().trim().toUpperCase();
        }

        /* Almost done.... */
        switch (game.getStatus()) {
            case IN_PROGRESS:
                System.out.println ("Thanks for playing!");
                break;
            case USER_WON:
                System.out.println ("Congratz");
                break;
            case USER_LOST:
                System.out.println ("Sorry....!");
                break;

        }
    }

    public static void main(String[] arg) {
        TextUI t = new TextUI();
        t.playLoop();
    }
}