Question

我试图在try {} catch {}方法之后访问变量（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();
}

将以某种方式创建ArrayList项目，并且我希望能够访问它。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();
}

但是我在try {} catch {}块中无法做任何事情，因为它说'它已经被创建了。

我希望能够创建一个程序，记住以前运行时的动作，但我似乎无法在正确的概念中取得领先。

Answer 1

您必须向外移动范围：

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
}

但是，让我给你一些提示：

不要在ArrayList()投入太多，请改为List<T>。
要非常小心你如何使用catch {} 有些事情（非常）错了，提供默认答案通常不是正确的政策。

Answer 2

您无需重新创建items变量，只需将其实例化即可。

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();
}

Answer 3

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();
}

从try {} catch {}访问变量

3 个答案: