這個塊爲什麼會拋出錯誤？

Question

「並非所有的代碼路徑返回一個值」

public BallData GetBall(String Name) 
    { 
     //Check each item in the list for the name. 
     foreach (BallData Item in _BallList) 
     { 
      //If the name matches, return the item to the caller and exit the loop. 
      if (Item.Name == Name) 
      { 
       return Item; 
      } 
      else 
      { 
       // Otherwise, throw an exception to indicate that the ball wasn't found. 
       throw new KeyNotFoundException("The ball name doesn't exist."); 
      } 


     } 
    } 

Answer 1

更改爲：

foreach (BallData Item in _BallList) 
{ 
      //If the name matches, return the item to the caller and exit the loop. 
      if (Item.Name == Name) 
      { 
       return Item; 
      } 

    } 
    throw new KeyNotFoundException("The ball name doesn't exist."); 

Answer 2

如果_BallList爲空，則什麼都不會返回。

Answer 3

如果_BallList是空的，你永遠不會進入循環，因此該方法不代碼返回任何