C#异常处理 [英] C# Exception handling

问题描述

我想知道是否有一种更雄辩的方式来表达下面的代码?我似乎无法使用IsNullOrEmpty方法来处理DataGridView中的数据，因此，每当单元格为null时，都会引发异常.

这可行，但似乎有点解决(也许没有解决)，并且在检查网格中复选框的值时遇到了相同的问题，这导致我为此编写了更多代码.

任何建议都将不胜感激.

I am wondering if there is a more eloquent way to express the code below? I can''t seem to get the IsNullOrEmpty method to work with data inside of a DataGridView so whenever a cell is null an exception is thrown.

This works, but it seems to be a bit of a work around (maybe not) and I have the same issue when checking the value of a checkbox in the grid which caused me to write more code for that work around.

Any suggestions are greatly appreciated.

private bool IsRowValid( DataGridViewRow row )
{
    bool retVal = false;
    try
    {
        if( ( string.IsNullOrEmpty( row.Cells[ "Quantity" ].Value.ToString() ) != true ) &&
            ( string.IsNullOrEmpty( row.Cells[ "Unit" ].Value.ToString() ) != true ) &&
            ( string.IsNullOrEmpty( row.Cells[ "Cell" ].Value.ToString() ) != true ) &&
            ( string.IsNullOrEmpty( row.Cells[ "Station" ].Value.ToString() ) != true ) )
        {
            retVal = true;
        }
    }
    catch( NullReferenceException )
    {
        retVal = false;
    }
    return retVal;
}

推荐答案

该代码中的问题是row.Cells[ "Quantity" ].Value可以是null，但是您在不检查该对象的情况下调用了ToString .

变更:

The problem in that code is that row.Cells[ "Quantity" ].Value can be null, but you call ToString on that without checking for that.

Change:

string.IsNullOrEmpty( row.Cells[ "Quantity" ].Value.ToString() )

到

to

string.IsNullOrEmpty( row.Cells[ "Quantity" ].Value as String)

顺便说一句，请不要执行!= true，这很难看，也不建议您这样做.而是这样做:

Btw please don''t do != true, that''s ugly to see and not recommended practice. Instead do this:

if( !String.IsNullOrEmpty(...))...

我不知道有什么更优雅的方法，尽管有人可能会知道.

我唯一要说的是，它可能会略短一些

I don''t know of a more elegant way, although somebody probably will.

The only thing I would say is that it could be very slightly shorter

if ( ( !string.IsNullOrEmpty( row.Cells[ "Quantity"].Value.ToString() )) &&
   ( !string.IsNullOrEmpty( row.Cells[ "Unit"].Value.ToString() )) &&
   ( !string.IsNullOrEmpty( row.Cells[ "Cell"].Value.ToString() )) &&
   ( !string.IsNullOrEmpty( row.Cells[ "Station"].Value.ToString() )) )

可能会牺牲可读性.

possibly at the expense of readability.

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