Objects and class objects cannot be converted?

[GoToLoop]

Replace private Map cars = new HashMap();
w/ final Map<String,Car> cars = new HashMap<String,Car>();

2D Array of TreeMaps wont access the intValue()

If you know how many you’re gonna need, you can simplify things a lot by choosing a vanilla array. You didn’t specify the generic datatypes for your TreeMap: Which seems like it is the pair color & int. So, their corresponding wrapper type is Integer: final TreeMap<Integer, Integer>[] colourRanges = new TreeMap[7];