用 java 实现 俄罗斯方块

实现俄罗斯方块的 Java 代码如下：

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.ArrayList;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Tetris extends JPanel {

    private static final long serialVersionUID = 1L;

    private final int width = 10;
    private final int height = 20;
    private final int size = 30;
    private final int top = 30;

    private int[][] grid = new int[width][height];

    private final Point[][][] shapes = {
        // I-Piece
        {
            { new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(3, 1) },
            { new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(1, 3) },
            { new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(3, 1) },
            { new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(1, 3) }
        },
        
        // J-Piece
        {
            { new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(2, 0) },
            { new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(2, 2) },
            { new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(0, 2) },
            { new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(0, 0) }
        },
        
        // L-Piece
        {
            { new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(2, 2) },
            { new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(0, 2) },
            { new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(0, 0) },
            { new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(2, 0) }
        },
        
        // O-Piece
        {
            { new Point(0, 0), new Point(0, 1), new Point(1, 0), new Point(1, 1) },
            { new Point(0, 0), new Point(0, 1), new Point(1, 0), new Point(1, 1) },
            { new Point(0, 0), new Point(0, 1), new Point(1, 0), new Point(1, 1) },
            { new Point(0, 0