检查字符串是否为空

伙计我有一个方法论证.我想在进一步指向程序的执行路径之前检查它的null或空字符串

我的方法是

public void DisplayCalcQuery(string argFromQueryBuilder)
{
    if ((argFromQueryBuilder.Trim() != null) || (argFromQueryBuilder.Trim() != ""))
    {
        //notify closure of query builder
        _QueryBuilderIsOpen = false;
        UserBuiltQueries.Add(argFromQueryBuilder);
        //displayng the user built query(queries) on the stack panel meant to display it. 
        var lastItem = UserBuiltQueries[UserBuiltQueries.Count - 1];
        //removing all $signs from the obtained string
        lastItem = lastItem.Replace(@"$", "");
        addBuiltCheck(lastItem); 
    }
    else
    {
        //notify closure of query builder
        _QueryBuilderIsOpen = false;
    }
}

但是,即使字符串正在"" 执行程序正在执行IF(我不想发生).