在類之間加載X位置給出了「字段永遠不會分配給」警告

Question

因此，我在XNA中創建了一個小型遊戲，並且正處於AI編碼階段。我目前的問題是我無法加載redNinja的X位置（玩家的角色），並讓藍色忍者（AI）讀取它並朝它走去。

每次我嘗試通過redNinja.Position.X引用它時，它會給我提示field is never assigned to, and will always have it's default value null.警告。

namespace Ninja_DM 
{ 
class AI 
{ 
    Texture2D blueNinja; 
    Ninjas redNinja; 
    float timer = 0f; 
    float interval = 130f; 
    int currentFrame = 0; 
    int spriteSpeed = 2; 
    int spriteWidth = 32; 
    int spriteHeight = 28; 
    public Rectangle sourceRect; 
    Vector2 position_b; 
    Vector2 origin; 

    public Vector2 Position 
    { 
     get { return position_b; } 
     set { position_b = value; } 
    } 

    public Vector2 Origin 
    { 
     get { return origin; } 
     set { origin = value; } 
    } 

    public Texture2D Texture 
    { 
     get { return blueNinja; } 
     set { blueNinja = value; } 
    } 

    public Rectangle SourceRect 
    { 
     get { return sourceRect; } 
     set { sourceRect = value; } 
    } 

    public AI(Texture2D texture, int currentFrame, int spriteWidth, int spriteHeight) 
    { 
     this.blueNinja = texture; 
     this.currentFrame = currentFrame; 
     this.spriteWidth = spriteWidth; 
     this.spriteHeight = spriteHeight; 
    } 

    public void AIMovement(GameTime gameTime) 
    { 
     sourceRect = new Rectangle(30 * currentFrame, 0, 30, 37); 

     if (position_b.X > redNinja.Position.X) 
     { 
      AnimateLeftAI(gameTime); 
      if (position_b.X < 20) 
      { 
       position_b.X += spriteSpeed; 
      } 
     } 

     if (position_b.X < redNinja.Position.X) 
     { 
      AnimateRightAI(gameTime); 
      if (position_b.X < 1100) 
      { 
       position_b.X += spriteSpeed; 
      } 
     } 

    } 

    public void AnimateLeftAI(GameTime gameTime) 
    { 

     timer += (float)gameTime.ElapsedGameTime.TotalMilliseconds; 

     if (timer > interval) 
     { 
      currentFrame++; 

      if (currentFrame > 4) 
      { 
       currentFrame = 3; 
      } 
      timer = 0f; 
     } 
    } 

    public void AnimateRightAI(GameTime gameTime) 
    { 

     timer += (float)gameTime.ElapsedGameTime.TotalMilliseconds; 

     if (timer > interval) 
     { 
      currentFrame++; 

      if (currentFrame > 4) 
      { 
       currentFrame = 3; 
      } 
      timer = 0f; 
     } 
    } 
} 
} 

Answer 1

你需要調用AIMovement（），這樣的事情時，給玩家帶來的忍者作爲參數：

public void AIMovement(GameTime gameTime, Ninjas playerNinja) 
{ 
    sourceRect = new Rectangle(30 * currentFrame, 0, 30, 37); 

    if (position_b.X > playerNinja.Position.X) 
    { 
     AnimateLeftAI(gameTime); 
     if (position_b.X < 20) 
     { 
      position_b.X += spriteSpeed; 
     } 
    } 

    if (position_b.X < playerNinja.Position.X) 
    { 
     AnimateRightAI(gameTime); 
     if (position_b.X < 1100) 
     { 
      position_b.X += spriteSpeed; 
     } 
    } 

} 

通知你真的不需要申報叫了一個字段變量因爲你將Ninjas帶入，因爲你正在測試這個方法的參數/參數。