Vector<Enemytank> enemytanks = new Vector<>(number);这段代码有什么意义和作用

这段代码创建了一个 Vector 对象 `enemytanks`，用于存储 `Enemytank` 类型的对象。其中，`number` 是一个整数类型的变量，表示初始化 Vector 对象时预留的空间大小，可以用于优化 Vector 对象的性能。

具体来说，当向 Vector 对象 `enemytanks` 添加元素时，如果当前 Vector 对象的容量已经满了，那么 Vector 对象就会自动扩容，以便能够添加新的元素。而如果在创建 Vector 对象时，指定了预留的空间大小，就可以避免过多的扩容操作，从而提高程序的性能。

因此，这段代码的意义和作用是创建一个能够存储多个 `Enemytank` 对象的 Vector 对象，并且通过指定预留的空间大小来优化程序的性能。

相关问题

java代码实现坦克大战

以下是Java实现坦克大战的示例代码：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TankWar extends JFrame implements ActionListener {

    private static final long serialVersionUID = 1L;

    // 游戏开始按钮
    private JButton startButton = new JButton("开始");

    // 游戏区域
    private GamePanel gamePanel = new GamePanel();

    public TankWar() {
        // 设置窗口标题
        setTitle("坦克大战");

        // 设置窗口大小
        setSize(800, 600);

        // 设置窗口可见性
        setVisible(true);

        // 设置关闭窗口时退出程序
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // 设置布局为边框布局
        setLayout(new BorderLayout());

        // 将游戏面板添加到窗口中央
        add(gamePanel, BorderLayout.CENTER);

        // 创建一个面板用于放置游戏开始按钮
        JPanel buttonPanel = new JPanel();

        // 将开始按钮添加到面板中
        buttonPanel.add(startButton);

        // 将面板添加到窗口南侧
        add(buttonPanel, BorderLayout.SOUTH);

        // 注册按钮事件监听器
        startButton.addActionListener(this);
    }

    // 实现按钮事件监听器接口
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == startButton) {
            // 当点击开始按钮时，开始游戏
            gamePanel.startGame();
        }
    }

    public static void main(String[] args) {
        new TankWar();
    }
}

class GamePanel extends JPanel implements Runnable, KeyListener {

    private static final long serialVersionUID = 1L;

    // 游戏线程
    private Thread gameThread;

    // 游戏是否正在进行中的标志
    private boolean isRunning = false;

    // 玩家坦克的初始位置
    private int playerX = 400, playerY = 500;

    // 玩家坦克的移动速度
    private int playerSpeed = 5;

    // 玩家坦克的方向
    private int playerDirection = 0;

    // 玩家坦克是否在移动中的标志
    private boolean isPlayerMoving = false;

    // 敌人坦克的列表
    private java.util.List<EnemyTank> enemyTanks = new java.util.ArrayList<EnemyTank>();

    // 子弹的列表
    private java.util.List<Bullet> bullets = new java.util.ArrayList<Bullet>();

    public GamePanel() {
        // 设置面板可获得焦点
        setFocusable(true);

        // 注册键盘事件监听器
        addKeyListener(this);
    }

    // 开始游戏
    public void startGame() {
        // 初始化敌人坦克
        for (int i = 0; i < 5; i++) {
            enemyTanks.add(new EnemyTank());
        }

        // 启动游戏线程
        gameThread = new Thread(this);
        gameThread.start();
    }

    // 绘制游戏界面
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        // 绘制玩家坦克
        g.setColor(Color.RED);
        g.fillRect(playerX, playerY, 30, 30);

        // 绘制敌人坦克
        for (EnemyTank enemyTank : enemyTanks) {
            g.setColor(Color.GREEN);
            g.fillRect(enemyTank.x, enemyTank.y, 30, 30);
        }

        // 绘制子弹
        for (Bullet bullet : bullets) {
            g.setColor(Color.BLACK);
            g.fillRect(bullet.x, bullet.y, 5, 5);
        }
    }

    // 线程运行方法
    public void run() {
        // 游戏开始
        isRunning = true;

        while (isRunning) {
            // 玩家坦克移动
            if (isPlayerMoving) {
                switch (playerDirection) {
                    case 0:
                        playerY -= playerSpeed;
                        break;
                    case 1:
                        playerX += playerSpeed;
                        break;
                    case 2:
                        playerY += playerSpeed;
                        break;
                    case 3:
                        playerX -= playerSpeed;
                        break;
                }
            }

            // 敌人坦克移动
            for (EnemyTank enemyTank : enemyTanks) {
                enemyTank.move();
            }

            // 子弹移动
            for (Bullet bullet : bullets) {
                bullet.move();

                // 检测子弹是否击中敌人坦克
                for (EnemyTank enemyTank : enemyTanks) {
                    if (bullet.x >= enemyTank.x && bullet.x <= enemyTank.x + 30 && bullet.y >= enemyTank.y && bullet.y <= enemyTank.y + 30) {
                        enemyTanks.remove(enemyTank);
                        bullets.remove(bullet);
                        break;
                    }
                }
            }

            // 重绘游戏界面
            repaint();

            // 等待一段时间
            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    // 按下键盘事件处理方法
    public void keyPressed(KeyEvent e) {
        switch (e.getKeyCode()) {
            case KeyEvent.VK_UP:
                playerDirection = 0;
                isPlayerMoving = true;
                break;
            case KeyEvent.VK_RIGHT:
                playerDirection = 1;
                isPlayerMoving = true;
                break;
            case KeyEvent.VK_DOWN:
                playerDirection = 2;
                isPlayerMoving = true;
                break;
            case KeyEvent.VK_LEFT:
                playerDirection = 3;
                isPlayerMoving = true;
                break;
            case KeyEvent.VK_SPACE:
                // 创建一颗子弹，并将其添加到子弹列表中
                bullets.add(new Bullet(playerX + 12, playerY + 12, playerDirection));
                break;
        }
    }

    // 松开键盘事件处理方法
    public void keyReleased(KeyEvent e) {
        switch (e.getKeyCode()) {
            case KeyEvent.VK_UP:
            case KeyEvent.VK_RIGHT:
            case KeyEvent.VK_DOWN:
            case KeyEvent.VK_LEFT:
                isPlayerMoving = false;
                break;
        }
    }

    // 忽略键入的字符事件处理方法
    public void keyTyped(KeyEvent e) {
    }
}

class EnemyTank {

    // 坦克位置
    public int x, y;

    // 坦克方向
    public int direction;

    // 坦克移动速度
    private int speed = 3;

    public EnemyTank() {
        // 初始化坦克位置
        x = (int) (Math.random() * 740);
        y = (int) (Math.random() * 500);

        // 初始化坦克方向
        direction = (int) (Math.random() * 4);
    }

    // 移动坦克
    public void move() {
        switch (direction) {
            case 0:
                y -= speed;
                break;
            case 1:
                x += speed;
                break;
            case 2:
                y += speed;
                break;
            case 3:
                x -= speed;
                break;
        }

        // 如果坦克碰到了边界，则改变方向
        if (x < 0 || x > 750 || y < 0 || y > 550) {
            direction = (direction + 2) % 4;
        }
    }
}

class Bullet {

    // 子弹位置
    public int x, y;

    // 子弹方向
    public int direction;

    // 子弹速度
    private int speed = 10;

    public Bullet(int x, int y, int direction) {
        // 初始化子弹位置和方向
        this.x = x;
        this.y = y;
        this.direction = direction;
    }

    // 移动子弹
    public void move() {
        switch (direction) {
            case 0:
                y -= speed;
                break;
            case 1:
                x += speed;
                break;
            case 2:
                y += speed;
                break;
            case 3:
                x -= speed;
                break;
        }
    }
}

这是一个简单的坦克大战实现，玩家可以控制坦克移动和发射子弹，敌人坦克会自动移动。注意，在实际开发中，还需要处理碰撞检测、爆炸效果等功能。

一份坦克大战的java代码

以下是一个简单的坦克大战游戏的 Java 代码，希望能对你有所帮助：

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.util.ArrayList;

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

public class TankWar extends JPanel implements KeyListener, Runnable {

    private static final long serialVersionUID = 1L;

    private JFrame frame;

    private Tank playerTank;
    private ArrayList<EnemyTank> enemyTanks;
    private ArrayList<Explosion> explosions;

    private BufferedImage offScreenImage;
    private Graphics offScreenGraphics;

    private boolean[] keys;

    public TankWar() {
        frame = new JFrame("Tank War");
        frame.setSize(800, 600);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        playerTank = new Tank(400, 500, Tank.Direction.UP, true);
        enemyTanks = new ArrayList<EnemyTank>();
        explosions = new ArrayList<Explosion>();

        for (int i = 0; i < 5; i++) {
            enemyTanks.add(new EnemyTank(50 + i * 150, 50, Tank.Direction.DOWN));
        }

        offScreenImage = new BufferedImage(800, 600, BufferedImage.TYPE_INT_ARGB);
        offScreenGraphics = offScreenImage.getGraphics();

        keys = new boolean[256];

        frame.addKeyListener(this);
        frame.add(this);
        frame.setVisible(true);

        new Thread(this).start();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        offScreenGraphics.setColor(Color.WHITE);
        offScreenGraphics.fillRect(0, 0, 800, 600);

        playerTank.draw(offScreenGraphics);

        for (EnemyTank enemyTank : enemyTanks) {
            enemyTank.draw(offScreenGraphics);
        }

        for (Explosion explosion : explosions) {
            explosion.draw(offScreenGraphics);
        }

        g.drawImage(offScreenImage, 0, 0, null);
    }

    @Override
    public void keyPressed(KeyEvent e) {
        keys[e.getKeyCode()] = true;

        if (keys[KeyEvent.VK_SPACE]) {
            playerTank.fire();
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
        keys[e.getKeyCode()] = false;
    }

    @Override
    public void keyTyped(KeyEvent e) {
    }

    @Override
    public void run() {
        while (true) {
            playerTank.move(keys);

            for (EnemyTank enemyTank : enemyTanks) {
                enemyTank.move();
            }

            for (int i = 0; i < playerTank.getMissiles().size(); i++) {
                Missile missile = playerTank.getMissiles().get(i);

                missile.move();

                if (missile.isOutOfBound()) {
                    playerTank.getMissiles().remove(missile);
                    i--;
                } else {
                    for (EnemyTank enemyTank : enemyTanks) {
                        if (missile.hit(enemyTank)) {
                            playerTank.getMissiles().remove(missile);
                            i--;
                            explosions.add(new Explosion(enemyTank.getX(), enemyTank.getY()));
                            enemyTanks.remove(enemyTank);
                            break;
                        }
                    }
                }
            }

            for (int i = 0; i < explosions.size(); i++) {
                Explosion explosion = explosions.get(i);

                if (explosion.isOver()) {
                    explosions.remove(explosion);
                    i--;
                }
            }

            for (EnemyTank enemyTank : enemyTanks) {
                for (int i = 0; i < enemyTank.getMissiles().size(); i++) {
                    Missile missile = enemyTank.getMissiles().get(i);

                    missile.move();

                    if (missile.isOutOfBound()) {
                        enemyTank.getMissiles().remove(missile);
                        i--;
                    } else {
                        if (missile.hit(playerTank)) {
                            enemyTank.getMissiles().remove(missile);
                            i--;
                            explosions.add(new Explosion(playerTank.getX(), playerTank.getY()));
                            playerTank.setAlive(false);
                            break;
                        }
                    }
                }

                if (playerTank.isAlive() && enemyTank.getRectangle().intersects(playerTank.getRectangle())) {
                    explosions.add(new Explosion(playerTank.getX(), playerTank.getY()));
                    playerTank.setAlive(false);
                    break;
                }
            }

            if (enemyTanks.isEmpty()) {
                System.out.println("You win!");
                System.exit(0);
            }

            if (!playerTank.isAlive()) {
                System.out.println("Game over!");
                System.exit(0);
            }

            repaint();

            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        new TankWar();
    }

    private class Tank {

        private int x;
        private int y;
        private Direction direction;

        private boolean alive;

        private Image[] images;
        private int currentImageIndex;

        private ArrayList<Missile> missiles;

        public Tank(int x, int y, Direction direction, boolean alive) {
            this.x = x;
            this.y = y;
            this.direction = direction;

            this.alive = alive;

            images = new Image[8];
            for (int i = 0; i < 8; i++) {
                images[i] = TankWarUtils.getImage("tank" + (i + 1) + ".png");
            }
            currentImageIndex = 0;

            missiles = new ArrayList<Missile>();
        }

        public void draw(Graphics g) {
            if (alive) {
                g.drawImage(images[currentImageIndex], x, y, null);
            } else {
                g.drawImage(TankWarUtils.getImage("explosion.png"), x, y, null);
            }

            for (Missile missile : missiles) {
                missile.draw(g);
            }
        }

        public void move(boolean[] keys) {
            int moveLength = 5;

            if (keys[KeyEvent.VK_UP]) {
                direction = Direction.UP;
                y -= moveLength;
            }

            if (keys[KeyEvent.VK_DOWN]) {
                direction = Direction.DOWN;
                y += moveLength;
            }

            if (keys[KeyEvent.VK_LEFT]) {
                direction = Direction.LEFT;
                x -= moveLength;
            }

            if (keys[KeyEvent.VK_RIGHT]) {
                direction = Direction.RIGHT;
                x += moveLength;
            }

            if (x < 0) {
                x = 0;
            }

            if (x > 750) {
                x = 750;
            }

            if (y < 0) {
                y = 0;
            }

            if (y > 550) {
                y = 550;
            }

            currentImageIndex++;

            if (currentImageIndex >= 8) {
                currentImageIndex = 0;
            }
        }

        public void fire() {
            missiles.add(new Missile(x + 20, y + 20, direction));
        }

        public int getX() {
            return x;
        }

        public int getY() {
            return y;
        }

        public Rectangle getRectangle() {
            return new Rectangle(x, y, 60, 60);
        }

        public ArrayList<Missile> getMissiles() {
            return missiles;
        }

        public boolean isAlive() {
            return alive;
        }

        public void setAlive(boolean alive) {
            this.alive = alive;
        }

        public enum Direction {
            UP, DOWN, LEFT, RIGHT
        }

    }

    private class EnemyTank {

        private int x;
        private int y;
        private Direction direction;

        private Image[] images;
        private int currentImageIndex;

        private ArrayList<Missile> missiles;

        public EnemyTank(int x, int y, Direction direction) {
            this.x = x;
            this.y = y;
            this.direction = direction;

            images = new Image[8];
            for (int i = 0; i < 8; i++) {
                images[i] = TankWarUtils.getImage("enemy" + (i + 1) + ".png");
            }
            currentImageIndex = 0;

            missiles = new ArrayList<Missile>();
        }

        public void draw(Graphics g) {
            g.drawImage(images[currentImageIndex], x, y, null);

            for (Missile missile : missiles) {
                missile.draw(g);
            }
        }

        public void move() {
            int moveLength = 3;

            if (Math.random() < 0.01) {
                fire();
            }

            if (Math.random() < 0.05) {
                int r = (int) (Math.random() * 4);
                if (r == 0) {
                    direction = Direction.UP;
                } else if (r == 1) {
                    direction = Direction.DOWN;
                } else if (r == 2) {
                    direction = Direction.LEFT;
                } else if (r == 3) {
                    direction = Direction.RIGHT;
                }
            }

            if (direction == Direction.UP) {
                y -= moveLength;
            } else if (direction == Direction.DOWN) {
                y += moveLength;
            } else if (direction == Direction.LEFT) {
                x -= moveLength;
            } else if (direction == Direction.RIGHT) {
                x += moveLength;
            }

            if (x < 0) {
                x = 0;
            }

            if (x > 750) {
                x = 750;
            }

            if (y < 0) {
                y = 0;
            }

            if (y > 550) {
                y = 550;
            }

            currentImageIndex++;

            if (currentImageIndex >= 8) {
                currentImageIndex = 0;
            }
        }

        public void fire() {
            missiles.add(new Missile(x + 20, y + 20, direction));
        }

        public int getX() {
            return x;
        }

        public int getY() {
            return y;
        }

        public Rectangle getRectangle() {
            return new Rectangle(x, y, 60, 60);
        }

        public ArrayList<Missile> getMissiles() {
            return missiles;
        }

        public enum Direction {
            UP, DOWN, LEFT, RIGHT
        }

    }

    private class Missile {

        private int x;
        private int y;
        private Direction direction;

        private Image image;

        public Missile(int x, int y, Direction direction) {
            this.x = x;
            this.y = y;
            this.direction = direction;

            image = TankWarUtils.getImage("missile.png");
        }

        public void draw(Graphics g) {
            g.drawImage(image, x, y, null);
        }

        public void move() {
            int moveLength = 8;

            if (direction == Direction.UP) {
                y -= moveLength;
            } else if (direction == Direction.DOWN) {
                y += moveLength;
            } else if (direction == Direction.LEFT) {
                x -= moveLength;
            } else if (direction == Direction.RIGHT) {
                x += moveLength;
            }
        }

        public boolean isOutOfBound() {
            return x < 0 || x > 800 || y < 0 || y > 600;
        }

        public boolean hit(Tank tank) {
            return getRectangle().intersects(tank.getRectangle());
        }

        public boolean hit(EnemyTank enemyTank) {
            return getRectangle().intersects(enemyTank.getRectangle());
        }

        public int getX() {
            return x;
        }

        public int getY() {
            return y;
        }

        public Rectangle getRectangle() {
            return new Rectangle(x, y, 10, 10);
        }

        public enum Direction {
            UP, DOWN, LEFT, RIGHT
        }

    }

    private class Explosion {

        private int x;
        private int y;

        private Image[] images;
        private int currentImageIndex;

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

            images = new Image[11];
            for (int i = 0; i < 11; i++) {
                images[i] = TankWarUtils.getImage("explosion" + (i + 1) + ".png");
            }
            currentImageIndex = 0;
        }

        public void draw(Graphics g) {
            g.drawImage(images[currentImageIndex], x, y, null);

            currentImageIndex++;

            if (currentImageIndex >= 11) {
                currentImageIndex = 0;
            }
        }

        public boolean isOver() {
            return currentImageIndex == 0;
        }

    }

    private static class TankWarUtils {

        public static Image getImage(String fileName) {
            return new ImageIcon(TankWarUtils.class.getResource("/images/" + fileName)).getImage();
        }

    }

}