java - createImage(int width，int height)问题

我有以下代码，作为游戏的一部分，每10毫秒运行一次：

private void gameRender()
{
    if(dbImage == null)
    {
        //createImage() returns null if GraphicsEnvironment.isHeadless()
        //returns true. (java.awt.GraphicsEnvironment)
        dbImage = createImage(PWIDTH, PHEIGHT);
        if(dbImage == null)
        {
            System.out.println("dbImage is null"); //Error recieved
            return;
        }
        else
        dbg = dbImage.getGraphics();
    }

    //clear the background
    dbg.setColor(Color.white);
    dbg.fillRect(0, 0, PWIDTH, PHEIGHT);

    //draw game elements...

    if(gameOver)
    {
        gameOverMessage(dbg);
    }
}

问题是即使我尝试定义图像后，它也会输入if语句来检查Image是否为空。我环顾四周，如果GraphicsEnvironment.isHeadless（）返回true，似乎createImage（）将返回null。

我不完全了解isHeadless（）方法的用途是什么，但我认为它可能与编译器或IDE有关，因此我尝试了两种方法，两者都得到相同的错误（Eclipse和BlueJ）。任何人都不知道错误的根源是什么，我该如何解决？

提前致谢

乔纳森

................................................... ........

编辑：
我正在使用java.awt.Component.createImage（int width，int height）。此方法的目的是确保创建并编辑包含游戏玩家视图的图像，该图像以后将通过JPanel绘制到屏幕上。
如果有帮助，这里还有一些代码：

public class Sim2D extends JPanel implements Runnable
{

private static final int PWIDTH = 500;
private static final int PHEIGHT = 400;
private volatile boolean running = true;
private volatile boolean gameOver = false;

private Thread animator;

//gameRender()
private Graphics dbg;
private Image dbImage = null;


public Sim2D()
{
    setBackground(Color.white);
    setPreferredSize(new Dimension(PWIDTH, PHEIGHT));

    setFocusable(true);
    requestFocus(); //Sim2D now recieves key events
    readyForTermination();

    addMouseListener( new MouseAdapter() {
        public void mousePressed(MouseEvent e)
        { testPress(e.getX(), e.getY()); }
    });
} //end of constructor

private void testPress(int x, int y)
{
    if(!gameOver)
    {
        gameOver = true; //end game at mousepress
    }
} //end of testPress()


private void readyForTermination()
{
    addKeyListener( new KeyAdapter() {
        public void keyPressed(KeyEvent e)
        { int keyCode = e.getKeyCode();
            if((keyCode == KeyEvent.VK_ESCAPE) ||
               (keyCode == KeyEvent.VK_Q) ||
               (keyCode == KeyEvent.VK_END) ||
               ((keyCode == KeyEvent.VK_C) && e.isControlDown()) )
            {
                running = false; //end process on above list of keypresses
            }
        }
    });
} //end of readyForTermination()

public void addNotify()
{
    super.addNotify(); //creates the peer
    startGame();       //start the thread
} //end of addNotify()

public void startGame()
{
    if(animator == null || !running)
    {
        animator = new Thread(this);
        animator.start();
    }
} //end of startGame()


//run method for world
public void run()
{
    while(running)
    {
        long beforeTime, timeDiff, sleepTime;

        beforeTime = System.nanoTime();

        gameUpdate(); //updates objects in game (step event in game)
        gameRender(); //renders image
        paintScreen(); //paints rendered image to screen

        timeDiff = (System.nanoTime() - beforeTime) / 1000000;
        sleepTime = 10 - timeDiff;

        if(sleepTime <= 0) //if took longer than 10ms
        {
            sleepTime = 5; //sleep a bit anyways
        }

        try{
            Thread.sleep(sleepTime); //sleep by allotted time (attempts to keep this loop to about 10ms)
        }
        catch(InterruptedException ex){}

        beforeTime = System.nanoTime();
    }

    System.exit(0);
} //end of run()

private void gameRender()
{
    if(dbImage == null)
    {
        dbImage = createImage(PWIDTH, PHEIGHT);
        if(dbImage == null)
        {
            System.out.println("dbImage is null");
            return;
        }
        else
        dbg = dbImage.getGraphics();
    }

    //clear the background
    dbg.setColor(Color.white);
    dbg.fillRect(0, 0, PWIDTH, PHEIGHT);

    //draw game elements...

    if(gameOver)
    {
        gameOverMessage(dbg);
    }
} //end of gameRender()

} //end of class Sim2D

希望这可以使事情有所清除，
乔纳森

最佳答案

我通常使用BufferedImage而不是createImage（...）。