Is there a more elegant way of adding an item to a Dictionary<> safely?

Question

I need to add key/object pairs to a dictionary, but I of course need to first check if the key already exists otherwise I get a \"key already exists in dictionary

Answer 1

Just use the indexer - it will overwrite if it's already there, but it doesn't have to be there first:

Dictionary currentViews = new Dictionary();
currentViews["Customers"] = "view1";
currentViews["Customers"] = "view2";
currentViews["Employees"] = "view1";
currentViews["Reports"] = "view1";

Basically use Add if the existence of the key indicates a bug (so you want it to throw) and the indexer otherwise. (It's a bit like the difference between casting and using as for reference conversions.)

If you're using C# 3 and you have a distinct set of keys, you can make this even neater:

var currentViews = new Dictionary()
{
    { "Customers", "view2" },
    { "Employees", "view1" },
    { "Reports", "view1" },
};

That won't work in your case though, as collection initializers always use Add which will throw on the second Customers entry.