Java HashMap iteration to find driving end event

Question

I'm working on a project where I have to determine when a driving event ends. A function is given an HashMap<Date, Integer> containing confidence levels of in vehicle/on foot in form of a percentage alongside a unix timestamp.

I'm attempting to iterate over this HashMap, determine if a driving event has ended.

I'm a PHP developer, and its a real challenge using Java logic like this, and I'm struggling to achieve something that should be simple. Any help appreciated.

Heres the logic I'm trying to implement:

If 
  we have at least 1 minute worth of data with 10 items in our HashMap 
then
  loop HashMap
     if past 30 seconds of time, from 30 seconds ago contain driving data of 60% confidence adverage or above then
     AND past 30 seconds of time from now contains working data with average 60% confidence or above
     then 
        mark isDriving as true
if isDriving == true 
then
   doSomething()`

My HashMap looks something like this:

private HashMap mActivityData = new HashMap<String, Long>();

mActivityData.putExtra("in_vehicle",80); // % confidence
mActivityData.putExtra("on_foot",10); // % confidence
mActivityData.putExtra("time",1461684458); // unix time stamp

Answer 1

This is only a partial answer.

You have mentioned "loop HashMap { ... } " in your question, but you can only loop over the keys of the hashmap. (or over the values with .values() )

To get the keys of a HashMap<Date, Integer> :

Set<Date> dates_unordered = my_hashmap.keySet ();

A Set is unordered, to order it use a function like this one to create an ordered list. (the "Date" class implements the "Comparable" interface which is needed for that sorting to work)

List<Date> dates_ordered = asSortedList (dates_unordered);

Iterate over the list.

Iterator<Date> it = dates_ordered.iterator (); // create an iterator object
while (it.hasNext ())
{
  Date d = it.next ();
  Integer i = my_hashmap.get (d); // access value in hashmap with this key

  // do something with "i" here
  // ...
}