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    <p>That's fine in most cases, though to make it optimized and (IMO) cleaner, what you could do is find a function to relate the input heading to one used in the map.</p> <p>For example: (I'm pretty sure this is right, but you'll want to check it)</p> <pre><code>45* (int)Math.round(( ((double)x % 360) / 45)) </code></pre> <p>What this does is first <code>x % 360</code> makes sure the heading is within a valid range. then </p> <pre><code>45 * round(.../45) </code></pre> <p>finds the closest multiple of 45.</p> <p>Now change your map to be </p> <pre><code> HashMap&lt;Integer, String&gt; map = new HashMap&lt;Integer, String&gt;() map.put(0, "North") map.put(45, "Northeast") etc... </code></pre> <p>So, now your algorithm becomes a fast mathemtical calculation rather than iterating through the map. Furthermore, you don't need as Hashtable here since it provides constructs for concurrency (if I remember correctly) and in your case it would actually cause a performance decrease.</p> <p>Once again, the performance hit may be completely negligible for your needs.</p> <p>Edit for Thilo's and shinjin's suggestions:</p> <p>Instead of multiplying by 45, just keep the rest of the equation, which gives you values for 0-7, and make an array of your strings.</p> <pre><code>String directions[] = {"N", "NE", "E", "SE", "S", "SW", "W", "NW"} return directions[ (int)Math.round(( ((double)x % 360) / 45)) % 8 ] </code></pre> <p>and you've got your problem solved in two lines.</p> <p>One note: Modulus won't work correctly for negative numbers. If our input heading is negative, you'll need to make it positive first.</p>
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    1. USReverend Gonzo
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    1. CO+1. Very nice. Taking this a step further, add another small conversion to the function and he can just get an index into an array of Strings: `String[] directions = { "N", "NE", "E" ... }`
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      1. USThilo
    2. COIf you omit the multiplication by 45, then you can use a simple array instead of a hash map.
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      1. USshinjin
    3. COYou need an additional "N" in that array. Headings 337.5 and up will round to 8.
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      1. USChristoffer Hammarström
 

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