string class disposable method

private void test()
{
    string tst = null;
    try
    {
        tst = "abc";     
    }
    catch (Exception)
    {
        throw;
    }
    finally
    开发者_运维知识库{
        tst = null;           
    }
}

My query is - Is it meaningful to type tst = null; in the finally block as the string class doesn't have the disposable method ?

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It doesn't have any effect, as tst goes out of scope immediately after the finally. And this has nothing to do with Dispose.

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No this is not necessary. The variable tst does no longer exists, when test() returns.

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Even if string implemented IDisposable, setting a variable to null wouldn't call the Dispose method. It's utterly pointless, as is the catch block with the throw.

If you see code like this in a codebase you're maintaining, rip it out and have a quiet word with whoever put it in there in the first place.