将图像从一个地方移动到另一个地方

Question

我有一个叫 enemy 的 class 和另一个叫 "goal" 的 class。目标是敌人必须向 "goal" 移动。所以我得到了 "goal" 的 X 和 Y 位置，但是当我在敌人 class 中实现它时，敌人应该移动但它没有。这是为什么？这是我到目前为止所做的。

Main Class:

public class GameManager extends JFrame implements KeyListener {

private int canvasWidth;
private int canvasHeight;
private int borderLeft;
private int borderTop;
private BufferedImage canvas;
private Stage stage;
private Enemy[] enemies;
private Player player;
private Goal goal;
private Graphics gameGraphics;
private Graphics canvasGraphics;
private int numEnemies;
private boolean continueGame;


public static void main(String[] args) {
    // During development, you can adjust the values provided in the brackets below
    // as needed. However, your code must work with different/valid combinations
    // of values.
    GameManager managerObj = new GameManager(1980, 1280, 30);
}

public GameManager(int preferredWidth, int preferredHeight, int maxEnemies) {
    this.borderLeft = getInsets().left;
    this.borderTop = getInsets().top;
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    if (screenSize.width < preferredWidth)
        this.canvasWidth = screenSize.width - getInsets().left - getInsets().right;
    else
        this.canvasWidth = preferredWidth - getInsets().left - getInsets().right;
    if (screenSize.height < preferredHeight)
        this.canvasHeight = screenSize.height - getInsets().top - getInsets().bottom;
    else
        this.canvasHeight = preferredHeight - getInsets().top - getInsets().bottom;

    setSize(this.canvasWidth, this.canvasHeight);
    setResizable(false);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);
    addKeyListener(this);

    Random rng = new Random(2);

    this.canvas = new BufferedImage(this.canvasWidth, this.canvasHeight, BufferedImage.TYPE_INT_RGB);

    // Create a Stage object to hold the background images
    this.stage = new Stage();

    // Create a Goal object with its initial x and y coordinates
    this.goal = new Goal(this.canvasWidth / 2, Math.abs(rng.nextInt()) % this.canvasHeight);

    // Create a Player object with its initial x and y coordinates
    this.player = new Player(this.canvasWidth - (Math.abs(rng.nextInt()) % (this.canvasWidth / 2)),
            (Math.abs(rng.nextInt()) % this.canvasHeight));

    // Create the Enemy objects, each with a reference to this (GameManager) object
    // and their initial x and y coordinates.
    this.numEnemies = maxEnemies;
    this.enemies = new Enemy[this.numEnemies];
    for (int i = 0; i < this.numEnemies; i++) {
        this.enemies[i] = new Enemy(this, Math.abs(rng.nextInt()) % (this.canvasWidth / 4),
                Math.abs(rng.nextInt()) % this.canvasHeight);
    }

    this.gameGraphics = getGraphics();
    this.canvasGraphics = this.canvas.getGraphics();
    this.continueGame = true;
    while (this.continueGame) {
        updateCanvas();
    }
    this.stage.setGameOverBackground();
    updateCanvas();
}


public void updateCanvas() {
    long start = System.nanoTime();
    // If the player is alive, this should move the player in the direction of the
    // key that has been pressed
    // Note: See keyPressed and keyReleased methods in the GameManager class.
    this.player.performAction();
    // If the enemy is alive, the enemy must move towards the goal. The goal object
    // is obtained via the GameManager object that is given at the time of creating
    // an Enemy object.
    // Note: The amount that the enemy moves must be much smaller than that of
    // the player above or else the game becomes hard to play.
    for (int i = 0; i < this.numEnemies; i++) {
        this.enemies[i].performAction();
    }

    if ((Math.abs(this.goal.getX() - this.player.getX()) < (this.goal.getCurrentImage().getWidth() / 2))
            && (Math.abs(this.goal.getY() - this.player.getY()) < (this.goal.getCurrentImage().getWidth() / 2))) {
        for (int i = 0; i < this.numEnemies; i++) {
            // Sets the image of the enemy to the "dead" image and sets its status to
            // indicate dead
            this.enemies[i].die();
        }
        // Sets the image of the enemy to the "dead" image and sets its status to
        // indicate dead
        this.goal.die();

        // Sets the background of the stage to the finished game background.
        this.stage.setGameOverBackground();
        this.continueGame = false;
    }

    // If an enemy is close to the goal, the player and goal die
    int j = 0;
    while (j < this.numEnemies) {
        if ((Math.abs(this.goal.getX() - this.enemies[j].getX()) < (this.goal.getCurrentImage().getWidth() / 2))
                && (Math.abs(this.goal.getY() - this.enemies[j].getY()) < (this.goal.getCurrentImage().getWidth()
                / 2))) {
            this.player.die();
            this.goal.die();
            this.stage.setGameOverBackground();
            j = this.numEnemies;
            this.continueGame = false;
        }
        j++;
    }
    try {
        // Draw stage
        this.canvasGraphics.drawImage(stage.getCurrentImage(), 0, 0, null);
        // Draw player
        this.canvasGraphics.drawImage(player.getCurrentImage(),
                this.player.getX() - (this.player.getCurrentImage().getWidth() / 2),
                this.player.getY() - (this.player.getCurrentImage().getHeight() / 2), null);
        // Draw enemies
        for (int i = 0; i < this.numEnemies; i++) {
            this.canvasGraphics.drawImage(this.enemies[i].getCurrentImage(),
                    this.enemies[i].getX() - (this.enemies[i].getCurrentImage().getWidth() / 2),
                    this.enemies[i].getY() - (this.enemies[i].getCurrentImage().getHeight() / 2), null);
        }

        // Draw goal
        this.canvasGraphics.drawImage(this.goal.getCurrentImage(),
                this.goal.getX() - (this.goal.getCurrentImage().getWidth() / 2),
                this.goal.getY() - (this.goal.getCurrentImage().getHeight() / 2), null);
    } catch (Exception e) {
        System.err.println(e.getMessage());
    }

    // Draw everything.
    this.gameGraphics.drawImage(this.canvas, this.borderLeft, this.borderTop, this);
    long end = System.nanoTime();
    this.gameGraphics.drawString("FPS: " + String.format("%2d", (int) (1000000000.0 / (end - start))),
            this.borderLeft + 50, this.borderTop + 50);
}

public Goal getGoal() {
    return this.goal;
}

public void keyPressed(KeyEvent ke) {
    // Below, the setKey method is used to tell the Player object which key is
    // currently pressed.
    // The Player object must keep track of the pressed key and use it for
    // determining the direction
    // to move.
    if (ke.getKeyCode() == KeyEvent.VK_LEFT)
        this.player.setKey('L', true);
    if (ke.getKeyCode() == KeyEvent.VK_RIGHT)
        this.player.setKey('R', true);
    if (ke.getKeyCode() == KeyEvent.VK_UP)
        this.player.setKey('U', true);
    if (ke.getKeyCode() == KeyEvent.VK_DOWN)
        this.player.setKey('D', true);
    if (ke.getKeyCode() == KeyEvent.VK_ESCAPE)
        this.continueGame = false;
}

@Override
public void keyReleased(KeyEvent ke) {
    // Below, the setKey method is used to tell the Player object which key is
    // currently released.
    // The Player object must keep track of the pressed key and use it for
    // determining the direction
    // to move.
    if (ke.getKeyCode() == KeyEvent.VK_LEFT)
        this.player.setKey('L', false);
    if (ke.getKeyCode() == KeyEvent.VK_RIGHT)
        this.player.setKey('R', false);
    if (ke.getKeyCode() == KeyEvent.VK_UP)
        this.player.setKey('U', false);
    if (ke.getKeyCode() == KeyEvent.VK_DOWN)
        this.player.setKey('D', false);
}

@Override
public void keyTyped(KeyEvent ke) {

}


}

Player Class:

private int myX;
private int myY;
private char d;


public Player(int i, int j) {
    // TODO Auto-generated constructor stub
    try {
        this.imageRunning = ImageIO.read(new File(
                "/Users/Desktop/images/player-alive.png"));
        this.imageOver = ImageIO.read(new File(
                "/Users/Desktop/images/player-dead.png"));
    } catch (IOException e) {
        e.printStackTrace();
    }

    this.imageCurrent = this.imageRunning;
    myX = i;
    myY = j;

}

public void performAction() {

}

public int getX() {

    return myX;
}

public int getY() {
    return myY;
}

public BufferedImage getCurrentImage() {
    return this.imageCurrent;
}

public void die() {
    this.imageCurrent = this.imageOver;
}


public void setKey(char c, boolean b) {

}

Answer 1

您需要在组件上重新绘制图形：

 gmY += 40;
 repaint(); /* add this where you want to redraw */

Answer 2

这只是改变了变量 gmX 和 gmY。而已。您需要在设置新的 gmX 和 gmY 值后更新框架。假设 frame 是你的 JFrame 对象，你需要这样的东西：

public void performAction() {
    gmX += 40;
    gmY += 40;
    frame.repaint();
}

将图像从一个地方移动到另一个地方

Move an image from one place to another

java

keyevent

jframe