java - 图像不显示..Java

Question

我正在尝试制作一个程序，其中有两个沿直线移动的图像，当它们读取帧的末尾时，它们会转动方向......但问题是，图像没有出现在屏幕上我不知道为什么..这是我的 Actor 类代码

public class Actor {



    private Image img;
    private int x,y,width,height;
    private final int RIGHT=1,LEFT=-1;
    private byte direction=RIGHT;
    public Actor(Image img, int x,int  y, int width, int height){
        this.x=x;
        this.y=y;
        this.width=width;
        this.height=height;

    }
    public Image getImg() {
        return img;
    }

    public void setImg(Image img) {
        this.img = img;
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    public int getWidth() {
        return width;
    }

    public void setWidth(int width) {
        this.width = width;
    }

    public int getHeight() {
        return height;
    }

    public void setHeight(int height) {
        this.height = height;
    }
    public void movement(int frameWidth){
        setX(getX()+direction);
        if(getX()<0) direction= RIGHT;
        if(getX()>(frameWidth-width)) direction= LEFT;
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub

    }

}

这是我的主课:

public class game extends JFrame implements Runnable{
    private int framewidth=1000;
    private int frameheight=1500;
    Image image= new ImageIcon("pics/buffy.png").getImage();
    Image image2= new ImageIcon("pics/buffythelayer.jpg").getImage();
    private Thread thread;
    private int picX=100;
    private int c=1;
    private int xSpeed=3;
    private int xFly=1;
    private int yFly=100;
    private Actor greenCar,pinkCar;
    public game(){
        setBounds(100,100,framewidth,frameheight);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
        thread= new Thread(this);
        thread.start();
        greenCar=new Actor(image,30,70,98,40);
        pinkCar=new Actor(image2,400,70,98,40);
    }
    public void paint(Graphics g){
        g.fillRect(xFly, yFly, 10, 10);
        g.drawImage(greenCar.getImg(), greenCar.getX(), greenCar.getY(), null);
        g.drawImage(pinkCar.getImg(), pinkCar.getX(), pinkCar.getY(), null);
        if(c==2){
        g.setColor(Color.CYAN);
        g.fillOval(100, 200, 150, 200);
        }
    }
    public static void main(String[] args) {
        new game();

    }

    public void run() {
        while(true)
        {
            xFly++;
            greenCar.movement(framewidth);
            pinkCar.movement(framewidth);
            /*if(picX>280){
                xSpeed=-xSpeed;
                picX=picX+xSpeed;
                c=2;
            }
            if(picX>=100){
                xSpeed=3;
            picX=picX+xSpeed;


            }*/

            repaint();
            try{
                thread.sleep(13);
            }
            catch(InterruptedException e){

            }

        }
        }

}

Answer 1

我想我看到了问题所在。当您运行下面的代码时，将最后一个值 ImageObserver 设置为 null。

g.drawImage(greenCar.getImg(), greenCar.getX(), greenCar.getY(), null);
g.drawImage(pinkCar.getImg(), pinkCar.getX(), pinkCar.getY(), null);

相反，你应该这样写:

g.drawImage(greenCar.getImg(), greenCar.getX(), greenCar.getY(), this);
g.drawImage(pinkCar.getImg(), pinkCar.getX(), pinkCar.getY(), this);

因此，JFrame 是图像加载时收到通知并可以正确绘制在屏幕上的对象。

如果情况并非如此，那么您应该将 super.paint(g) 添加到您的绘制方法中。

你的paint(g)方法应该是这样的:

public void paint(Graphics g){
    super.paint(g);
    g.fillRect(xFly, yFly, 10, 10);
    g.drawImage(greenCar.getImg(), greenCar.getX(), greenCar.getY(), this);
    g.drawImage(pinkCar.getImg(), pinkCar.getX(), pinkCar.getY(), this);
    if(c==2){
    g.setColor(Color.CYAN);
    g.fillOval(100, 200, 150, 200);
    }
}

我希望这会有所帮助。