Java HashMap VS C# Dictionary

Java Code:

HashMap< String , String > hm = new HashMap< String , String >();
hm.put("A", "A--Content");
hm.put("B", "B--Content");
//Get all value
for(Iterator< String > it = hm.keySet().iterator(); it.hasNext();){
    String key = it.next();
    System.out.println("Key: "+ key + ", value: "+hm.get(key));
}
//Get specific value
System.out.println(hm.get("A"));

C# Code:

Dictionary< string , string > dict = new Dictionary< string , string >();
try
{
    dict.Add("A", "A--Content");
    dict.Add("B", "B--Content");
    //Get all value
    foreach (KeyValuePair< string , string > kvp in dict)
    {
        Console.WriteLine("key: {0}, value: {1}", kvp.Key, kvp.Value);
    }
    //Get specific value
    string val = "";
    dict.TryGetValue("A", out val);
    Console.WriteLine("value="+val);
    //or
    Console.WriteLine("value=" + dict["A"]);
}
catch (Exception)
{
    //The method "Add" will throw exception if key already existed!!!
    Console.WriteLine("Can't insert same key");
}