按下组合键时，Java程序会发出错误蜂鸣声

Question

我的代码可以生成与在海洋中航行的船的不同方向相对应的射弹。方向由物体的速度决定，顺时针循环，其中0为北至7为西北。在我的keyPressed功能中，我可以用箭头键移动就好了。此外，如果我按空格按钮激活大炮，一切都很顺利，除非我向西北方向前进。在这种情况下，没有发射子弹，我的java程序发出一点哔声。

keyPressed代码

 public void keyPressed(KeyEvent e) { //TODO switch to keyBindings to remove pause after the initial key press
    // if the key is pressed, move up
    if(e.getKeyCode() == KeyEvent.VK_DOWN){
        //move the board down.
        dy = speed;
    }
    if(e.getKeyCode() == KeyEvent.VK_UP){
        // move spaceship upwards
        dy = -speed;
    }
    if(e.getKeyCode() == KeyEvent.VK_LEFT){
        dx = -speed;
    }
    if(e.getKeyCode() == KeyEvent.VK_RIGHT){
        dx = speed;
    }
    dir = myShip.getDirection(dx, dy); // determine direction so that the draw function can draw the correct sprite.
    if(e.getKeyCode() == KeyEvent.VK_I){ // info key.
        System.out.println(getCurrentTile().getClass().getName()); 
        Tile t = getCurrentTile();
        if(t.isDockTile()){
            Docks d = (Docks) t;
            System.out.println(d.getName());
        }
    }
    if(e.getKeyCode() == KeyEvent.VK_M && getCurrentTile().isDockTile()){ 
        if(getCurrentTile().isDockTile()){
            mission = new Mission(); // create a new mission.
            Docks d = (Docks) getCurrentTile();
            mission.init(d); // initialize using the dock's name.
            isMissionAssigned = true; // yay! we have a Mission!
        } else {
            System.out.println("You can't get a mission if you're not at a port!");
        }
    }
    // fire a bullet 
    if(e.getKeyCode() == KeyEvent.VK_SPACE){ // TODO - NW seems to be broken.     
            bullet = new Projectile(bulletSpeed, dir, 10);
            System.out.println("Created a bullet with direction " + dir);
            bullet2 = new Projectile(bulletSpeed, myShip.getOppDir(dir), 10);

    }       
}

我的两个功能是获得船的方向。

public int getOppDir(int d){
    // since there are 4 directions, add 4 to get opposite.
    // use opposite to move back to 0 if > than 8
    for(int i = 0; i < 4; i++){
        d++;
        if(d >= 8){
            d = 0;
        }
    }
    return d;

}

public int getDirection(int dx, int dy){ // determines the direction the ship is facing based on speeds.
    // 0 = N, 1 = ne, 2 = e, 3 = se, 4 = s, 5 = sw, 6 = w, 7 = nw
    int tempDir = 0;
    if( dx == 0 && dy < 0){
        // north
        tempDir = 0;
    } else if(dx == 0 && dy > 0){
        // south
        tempDir = 4;

    } else if(dx > 0 && dy == 0){
        // east
        tempDir = 2;
    } else if(dx > 0 && dy < 0){
        // ne
        tempDir = 1;
    } else if( dx > 0 && dy > 0)    {
        // se
        tempDir = 3;
    } else if(dx < 0 && dy == 0){
        // west
        tempDir = 6;            
    } else if (dx < 0 && dy < 0){
        //northWest
        tempDir = 7;
    } else if(dx < 0 && dy > 0){
        //south west
        tempDir = 5;
    }
    return tempDir; 
}

提前感谢您的帮助！

编辑：我认为这是一个硬件问题。转换到ASDW控件而不是箭头键解决了问题。