Cardinal direction algorithm in Java -

At the end of this week, I will take an algorithm that takes a title (in degrees) and back together for a string Beating spend a few minutes on the main direction (I'm using it in an Android Compass app). I ended up with it:

  Private string headingtoostring (float heading) {string strHeading = "?"; Hashtable & lt; String, float & gt; Cardinal = new hashtable & lt; String, float & gt; (); Cardinal.put ("North_1", new Float (0)); Cardinal.put ("Northeast", New Float (45)); Cardinal.put ("East", New Float (90)); Cardinal.put ("southeast", new float (135)); Cardinal.put ("south", new float (180)); Cardinal.put ("south west", new float (225)); Cardinal.put ("west", new float (270)); Cardinal.put ("Northwest", New Float (315)); Cardinal.put ("North_2", new float (360)); For (string key: cardinal.keySet ()) {float value = cardinal.get (key); If (mathematics.base (title - value) <30) {strHeading = key; If (key.contains ("North_")) {strHeading = "North"; }             break; }} Return Strawing; }  

My question is, is this the best way to do it? It should have been done several times earlier, although I have not yet searched for examples on the web.

Solution

[East] Public stable String HeadingString 2 (Double X) {String Directions [] = {"N", "NE", "E", "SE", "S", "SW", "W", "NW", "N"} ; Returning directions [(int) Mathrade ((((x) x% 360) / 45); } "

In most cases this is fine, although it is optimized and (IMO) cleaner For what you can do, you can find a function to address the input title used in the map.

For example: (I'm pretty sure this is correct, but you want to see it)

  45 * (int) Mathround (((((double) X% 360) / 45))  

This is the first X% 360 ensures that the title is within a valid range.

finds 45 * round (... / 45)

45 near priceless.

Now change your map

hashmap < Integer, string & gt; Map = new hashmap & lt; Integer, string & gt; Map.put (0, "answer") map.put (45, "Northeast") etc ...

So, now instead of roaming through the algorithm map, The calculation becomes. In addition, you do not have to have a handshake because it creates concurrency (if I remember correctly) and in your case it actually reduced performance.

Once again, the performance hits can be completely negligible for your needs.

Edit for Thilo and Shinjin's suggestions:

Instead of multiplying by 45, keep the rest of the equation, which gives value to 0-7, and string directions [] = {"N", "NE", "E", "SE", "S", "SW", "W" [String Guideline] [/ p], "NW"} Return Directions [(Int) Math Field (((double (double) x% 360) / 45))% 8]

And you have solved your problem in two rows.

A Note: Modulus will not work properly for negative numbers. If our input title is negative, then you have to make it positive earlier.