XNA 非静态字段、方法或属性错误需要对象引用

Question

我在互联网上做了一些研究，包括这个网站，但我仍然对如何处理这个错误感到困惑。我有 2 个类，我正在使用 MainSkeleton，它是 Game1 类，它具有 move 方法，同时我还创建了一个处理用户输入的 InputSkeleton 类。当我尝试调用 move 方法时，即使我调用了类，我也会收到错误。

主骨架

    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class MainSkeleton: Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        InputSkeleton input;
        SpriteBatch spriteBatch;
        Color backColor = Color.CornflowerBlue;
        public MainSkeleton()
        {
            input = new InputSkeleton(1); 
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";

        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            // TODO: Add your initialization logic here

            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        // This is a texture we can render.
        Texture2D myTexture;

        // Set the coordinates to draw the sprite at.
        Vector2 spritePosition = Vector2.Zero;

        // Store some information about the sprite's motion.
        Vector2 spriteSpeed = new Vector2(50.0f, 50.0f);
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);
            myTexture = Content.Load<Texture2D>("Person");
            // TODO: use this.Content to load your game content here
        }

        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            // Allows the game to exit
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();

            // TODO: Add your update logic here
            input.Update();

            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // Draw the sprite.
            spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend);
            spriteBatch.Draw(myTexture, spritePosition, Color.White);
            spriteBatch.End();

            base.Draw(gameTime);
        }
       public void Move(String direction)
        {
            int MaxX = graphics.GraphicsDevice.Viewport.Width - myTexture.Width;
            int MinX = 0;
            int MaxY = graphics.GraphicsDevice.Viewport.Height - myTexture.Height;
            int MinY = 0;
            if (direction.Equals("up"))
            {
                if (spritePosition.Y > MinY)
                {
                    spritePosition.Y = spritePosition.Y - 1;
                }
                else
                {
                    spritePosition.Y = MinY;
                }
            }
            if (direction.Equals("down"))
            {
                if (spritePosition.Y < MaxY)
                {
                    spritePosition.Y = spritePosition.Y + 1;
                }
                else
                {
                    spritePosition.Y = MaxY;
                }
            }
            if (direction.Equals("left"))
            {
                if (spritePosition.X > MinX)
                {
                    spritePosition.X = spritePosition.X - 1;
                }
                else
                {
                    spritePosition.X = MinX;
                }
            }
            if (direction.Equals("right"))
            {
                if (spritePosition.X < MaxX)
                {
                    spritePosition.X = spritePosition.X + 1;
                }
                else
                {
                    spritePosition.X = MinX;
                }
            }
        }
    }

输入骨架

    public class InputSkeleton
    {
        public KeyboardState newKState;
        public KeyboardState oldKState;
        public MouseState newMState;
        public MouseState oldMState;
        public Boolean menuState;
        public Boolean gameRun;
        public int player;
        public InputSkeleton(int p)
        {
            player = p;

        }


        public void Update()
        {
            if (menuState == true && gameRun == false)
            {
                MenuInput();
            }
            else if (menuState == false && gameRun == true)
            {
                PlayerInput();
            }

        }
        public void MenuInput()
        {
        }
        public void PlayerInput()
        {

            newKState = Keyboard.GetState();
            if (newKState.IsKeyDown(Keys.Up))
            {
                MainSkeleton.Move("up");
            }
            if (newKState.IsKeyDown(Keys.Down))
            {
                MainSkeleton.Move("down");
            }
            if (newKState.IsKeyDown(Keys.Left))
            {
                MainSkeleton.Move("left");
            }
            if (newKState.IsKeyDown(Keys.Right))
            {
                MainSkeleton.Move("right");
            }
            oldKState = newKState;
        }
    }

Answer 1

静态方法可以在类上调用，而非静态方法需要在对象上调用。您正在尝试在类上调用非静态方法；

MainSkeleton.Move("up");

要么您需要将 Move() 方法设为静态方法（在这种情况下，这不是一个选项，因为您希望每次都在同一个对象上调用该方法），或者您需要以某种方式获取原始 @ 987654323@ 对象并在其上调用方法。

获取原始对象的一种简单方法是将其传递给您从 MainSkeleton 调用的 InputObject 构造函数；

input = new InputSkeleton(1, this);   // Pass in myself

...并在构造函数中获取对象；

MainSkeleton mainSkeleton;

public InputSkeleton(int p, MainSkeleton m)
{
    player = p;
    mainSkeleton = m;
}

...最后在对象上调用move()；

mainSkeleton.Move("up");

Answer 2

问题是您在没有创建实例的情况下调用该类。 您需要首先创建一个实例来调用类中的非静态方法。 示例；

private MainSkeleton _MainSkeleton = new MainSkeleton();

private void Update()
{
    // The below is calling a method and telling what object is calling that method.
    _MainSkeleton.Move("right");
    // The below calls a method but does not link to any object. The below is only able to call non-static methods. 
    MainSkeleton.Move("right");
}

您应该查看更多关于静态与非静态方法的信息，看看有什么区别。