从 try{} catch{} 访问变量

本文关键字：变量 访问 catch try | 更新日期: 2023-09-27 18:35:12

我试图在try{} catch{}方法之后访问一个变量（特别是ArrayList）。

try 
{
//Here I would import data from an ArrayList if it was already created.
}
catch
{  
//Create new array list if it couldn't find one.
ArrayList items = new ArrayList();
}

无论如何，将创建 ArrayList 项，我希望能够访问它。我之前尝试初始化 ArrayList，如下所示：

ArrayList items;
try 
{
//Here I would import data from an ArrayList if it was already created.
}
catch
{  
//Create new array list if it couldn't find one.
ArrayList items = new ArrayList();
}

但是我无法在 try{} catch{} 块中做任何事情，因为它说'它已经被创建。

我希望能够创建一个程序来记住以前运行时的操作，但我似乎无法围绕正确的概念取得进展。

从 try{} catch{} 访问变量

您必须将范围向外移动：

ArrayList items;    // do not initialize
try 
{
   //Here I would import data from an ArrayList if it was already created.
   items = ...;
}
catch
{  
  //Create new array list if it couldn't find one.
  items = new ArrayList();  // note no re-declaration, just an assignment
}

但让我给你一些提示：

  • 不要在ArrayList()上投入太多，而是看List<T>。
  • 非常小心如何使用catch {}。
    有些事情（非常）出错，提供默认答案通常不是正确的策略。

您不需要重新创建 items 变量，只需实例化它即可。

ArrayList items;
try 
{
    //Here I would import data from an ArrayList if it was already created.
}
catch
{  
    //Create new array list if it couldn't find one.
    items = new ArrayList();
}

试试这个：

ArrayList items;
try 
{
   //Here I would import data from an ArrayList if it was already created.
}
catch
{  
   //Create new array list if it couldn't find one.
   items = new ArrayList();
}
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