I am a beginner learning Java, and I coded a command line version of the game 2048 for practice. Any feedback, especially regarding best practices, object-oriented principles, and tidying up the code logic, is appreciated.
import java.util.Scanner;
class Cell {
int value = 0;
boolean hasMerged = false;
}
class Game {
final int BOARD_SIZE = 4;
Cell[][] cells;
void create() {
cells = new Cell[BOARD_SIZE][BOARD_SIZE];
for (int i = 0; i < BOARD_SIZE; i++) {
for (int j = 0; j < BOARD_SIZE; j++) {
cells[i][j] = new Cell();
cells[i][j].value = 0;
}
}
}
int rowStart = 0;
int columnStart = 0;
int rowStep = 0;
int columnStep = 0;
int nextRow = 0;
int nextColumn = 0;
//to be used for move() and isLegal()
void setDirection (char direction) {
switch (direction) {
case 'W':
rowStart = 1;
columnStart = 0;
rowStep = 1;
columnStep = 1;
nextRow = -1;
nextColumn = 0;
break;
case 'A':
rowStart = 0;
columnStart = 1;
rowStep = 1;
columnStep = 1;
nextRow = 0;
nextColumn = -1;
break;
case 'S':
rowStart = 2;
columnStart = 0;
rowStep = -1;
columnStep = 1;
nextRow = 1;
nextColumn = 0;
break;
case 'D':
rowStart = 0;
columnStart = 2;
rowStep = 1;
columnStep = -1;
nextRow = 0;
nextColumn = 1;
break;
}
}
void move() {
boolean changed = true;
while (changed) {
changed = false;
for (int i = rowStart; i >= 0 && i < BOARD_SIZE; i += rowStep) {
for (int j = columnStart; j >= 0 && j < BOARD_SIZE; j += columnStep) {
if (cells[i][j].value != 0 && cells[i + nextRow][j + nextColumn].value == 0) {
changed = true;
cells[i + nextRow][j + nextColumn].value = cells[i][j].value;
cells[i + nextRow][j + nextColumn].hasMerged = cells[i][j].hasMerged;
cells[i][j].value = 0;
cells[i][j].hasMerged = false;
}
else if (cells[i][j].value != 0 && cells[i + nextRow][j + nextColumn].value == cells[i][j].value && !(cells[i][j].hasMerged || cells[i + nextRow][j + nextColumn].hasMerged)) {
changed = true;
cells[i + nextRow][j + nextColumn].value *= 2;
cells[i + nextRow][j + nextColumn].hasMerged = true;
cells[i][j].value = 0;
cells[i][j].hasMerged = false;
}
}
}
}
for (int i = 0; i < BOARD_SIZE; i++) {
for (int j = 0; j < BOARD_SIZE; j++) {
cells[i][j].hasMerged = false;
}
}
}
void generateRandomCell() {
int count = 0;
int[][] empty = new int[16][2];
for (int i = 0; i < BOARD_SIZE; i++) {
for (int j = 0; j < BOARD_SIZE; j++) {
if (cells[i][j].value == 0) {
empty[count][0] = i;
empty[count][1] = j;
count += 1;
}
}
}
int randomIndex = (int) (Math.random() * count);
if (Math.random() < 0.9) {
cells[empty[randomIndex][0]][empty[randomIndex][1]].value = 2;
}
else {
cells[empty[randomIndex][0]][empty[randomIndex][1]].value = 4;
}
}
boolean isLegal() {
for (int i = rowStart; i >= 0 && i < BOARD_SIZE; i += rowStep) {
for (int j = columnStart; j >= 0 && j < BOARD_SIZE; j += columnStep) {
if (cells[i][j].value != 0 && (cells[i + nextRow][j + nextColumn].value == 0 || cells[i][j].value == cells[i + nextRow][j + nextColumn].value)) {
return true;
}
}
}
return false;
}
boolean isOver() {
char[] directions = {'W', 'A', 'S', 'D'};
for (int i = 0; i < BOARD_SIZE; i++) {
setDirection(directions[i]);
if (isLegal()) {
return false;
}
}
return true;
}
void printBoard() {
int width = 5;
int space;
System.out.print("\n");
for (int i = 0; i < BOARD_SIZE; i++) {
for (int j = 0; j < BOARD_SIZE; j++) {
space = width - String.valueOf(cells[i][j].value).length();
if (cells[i][j].value != 0) {
System.out.print(cells[i][j].value);
}
else
{
System.out.print("_");
}
System.out.print(" ".repeat(space));
}
System.out.print("\n\n");
}
System.out.println("");
}
}
class Game2048 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
Game game = new Game();
game.create();
game.generateRandomCell();
System.out.print("\n\nHello!\nEnter W, A, S, D to move, and Q to quit.\n\n");
while (!game.isOver()) {
game.printBoard();
System.out.println("Enter your move: ");
String userInput = scanner.nextLine();
if (userInput.length() != 1) {
System.out.print("\nInvalid!\n");
continue;
}
char userMove = userInput.charAt(0);
if (userMove == 'Q') {
System.exit(0);
}
else if (userMove != 'W' && userMove != 'A' && userMove != 'S' && userMove != 'D') {
System.out.print("\nInvalid!\n");
continue;
}
game.setDirection(userMove);
if (game.isLegal()) {
game.move();
game.generateRandomCell();
}
else {
System.out.print("\nIllegal!\n");
}
}
System.out.println("Game over!");
}
}
