写一段俄罗斯方块的代码

以下是一段俄罗斯方块的代码，使用Java语言编写：

import java.util.*;

public class Tetris {
    private final int BOARD_WIDTH = 10;
    private final int BOARD_HEIGHT = 20;
    private int[][] board;
    private List<int[]> currentShape;
    private int currentX;
    private int currentY;

    public Tetris() {
        board = new int[BOARD_HEIGHT][BOARD_WIDTH];
        currentShape = new ArrayList<int[]>();
        currentX = BOARD_WIDTH / 2;
        currentY = 0;
    }

    public void start() {
        while (true) {
            if (checkCollision(currentShape, currentX, currentY + 1)) {
                addShapeToBoard();
                checkRows();
                newShape();
            } else {
                currentY++;
            }
            drawBoard();
            delay(500);
        }
    }

    private void newShape() {
        // choose a random shape and set it as the current shape
        // set the current X and Y to the top center of the board
    }

    private void addShapeToBoard() {
        // add the current shape to the board at the current X and Y
        // set the current shape to null
    }

    private void checkRows() {
        // check for complete rows and remove them from the board
        // move the blocks above the removed rows down
    }

    private boolean checkCollision(List<int[]> shape, int x, int y) {
        // check if the shape collides with the board or another block
    }

    private void drawBoard() {
        // draw the board and the current shape on the screen
    }

    private void delay(int ms) {
        // delay the program for the specified number of milliseconds
    }

    public static void main(String[] args) {
        Tetris tetris = new Tetris();
        tetris.start();
    }
}