Java HashMap: How to get a key and value by index?

Question

I am trying to use a HashMap to map a unique string to a string ArrayList like this:

HashMap>

Basical

Answer 1

HashMaps don't keep your key/value pairs in a specific order. They are ordered based on the hash that each key's returns from its Object.hashCode() method. You can however iterate over the set of key/value pairs using an iterator with:

for (String key : hashmap.keySet()) 
{
    for (list : hashmap.get(key))
    {
        //list.toString()
    }
}