Question

好的，所以在我正在开发的XNA 4.0游戏中我遇到了这个问题，其中一个方法是获取错误'并非所有代码路径都返回一个值'而且这一直让我感到疯狂过了几个小时。

 private Rectangle HandleCollision(Rectangle bounds, TileCollision collision, Rectangle tileBounds)
    {
        Vector2 depth = RectangleExtensions.GetIntersectionDepth(bounds, tileBounds);
        if (depth != Vector2.Zero)
        {
            float absDepthX = Math.Abs(depth.X);
            float absDepthY = Math.Abs(depth.Y);

            // Resolve the collision along the shallow axis.  
            if (absDepthY < absDepthX || collision == TileCollision.Platform)
            {
                // If we crossed the top of a tile, we are on the ground.
                // also ladder
                if (previousBottom <= tileBounds.Top)
                {
                    if (collision == TileCollision.Ladder)
                    {
                        if (!isClimbing && !isJumping)
                        {
                            //walking over a ladder
                            isOnGround = true;
                        }
                    }
                    else
                    {
                        isOnGround = true;
                        isClimbing = false;
                        isJumping = false;
                    }
                }


                // Ignore platforms, unless we are on the ground.  
                if (collision == TileCollision.Impassable || IsOnGround)
                {
                    // Resolve the collision along the Y axis.  
                    Position = new Vector2(Position.X, Position.Y + depth.Y);

                    // Perform further collisions with the new bounds.  
                    bounds = BoundingRectangle;
                }
            }
            else if (collision == TileCollision.Impassable) // Ignore platforms.  
            {
                // Resolve the collision along the X axis.  
                Position = new Vector2(Position.X + depth.X, Position.Y);

                // Perform further collisions with the new bounds.  
                bounds = BoundingRectangle;
            }

            else if (collision == TileCollision.Ladder && !isClimbing)
            {
                //stops colliding with ladder if player walks past or drops off ladder
                Position = new Vector2(Position.X, Position.Y);

                //perform collisions with new bounds
                bounds = BoundingRectangle;
            }
            return bounds;
        }
    }

理解这个错误的任何帮助都将不胜感激，谢谢。

Answer 1

您的问题就在这里。

if (depth != Vector2.Zero)

如果此计算结果为false，则不返回任何内容。

Answer 2

将return bounds;语句移到if语句之外。如果if语句解析为false，则永远不会命中返回。

Answer 3

如果深度等于Vector2.Zero，则不返回任何内容。因此，并非所有代码路径都返回一个值。

Answer 4

如果您的depth != Vector2.Zero返回false

，该怎么办？

if ( depth != Vector2.Zero )

条件？

此时您的方法不返回任何内容。您必须在此循环之外返回值。

Answer 5

return语句嵌套在条件内。因此，如果（depth == Vector2.Zero），该方法将不返回值。

Answer 6

这是因为如果你首先IF会返回false，那么错误就是Not all code paths return a value。您应该考虑添加一个返回值，或者可能是该案例的例外

Answer 7

您需要将最终返回值移至if：

之外

private Rectangle HandleCollision(Rectangle bounds, TileCollision collision, Rectangle tileBounds)
{
  if(depth != Vector2.Zero)
  {

  }
  return bounds;
}

你是这样的：

private Rectangle HandleCollision(Rectangle bounds, TileCollision collision, Rectangle tileBounds)
{
  if(depth != Vector2.Zero)
  {
     return bounds;
  }
}

这意味着，如果depth == Vector2.Zero没有返回任何内容，那么您将收到您所看到的错误。

方法：并非所有代码路径都返回值

7 个答案: