If you want to iterate through the set of double values assigned to a particular letter in the map, you can do the following:
for (double i : map.get('A')) {
System.out.println(i);
}
If instead you want to iterate through the first double value assigned to each letter value in the map:
for (char i : map.keySet()) {
System.out.println(map.get(i)[0]);
}