Simple example

Lets see a simple example:

If we have an address like

'Hauptbahnhof, Hamburg' resolves to the latitude and longitude:

53.5526394, 10.0067103

This we can use than to calculate the geohash code like this:

String geohash = GeoHashExtensions.encode(53.5526394, 10.0067103);

double [] decoded = GeoHashExtensions.decode(geohash);

System.out.println("geohash:"+geohash);

System.out.println(decoded[0]+ ", "+ decoded[1]);`

Output: geohash:u1x0esywtr81 53.55263943783939, 10.006710458546877

As we can see we can reverse this process too with the method GeoHashExtensions.decode(geohash).

More interesting it gets if you like to find the neigbors regions from one geohash point. There are 2 methods to get this information:

geohash = geohash.substring(0, 7);

Map adjacentAreas = GeoHashExtensions.getAllAdjacentAreasMap(geohash);

System.out.println(adjacentAreas);

System.out.println("=======================================");

List aa = GeoHashExtensions.getAllAdjacentAreasList(geohash);

System.out.println(aa);

Output:

{center=u1x0esy, top=u1x0esz, bottom=u1x0esv, right=u1x0etn, left=u1x0esw, topleft=u1x0esx, topright=u1x0etp, bottomright=u1x0etj, bottomleft=u1x0est}

=======================================

\[u1x0esy, u1x0esz, u1x0etp, u1x0etn, u1x0etj, u1x0esv, u1x0est, u1x0esw, u1x0esx\]

So the geohash from the given address is: 'u1x0esywtr81'.

To get a box around this point we can truncate this geohash to: 'u1x0esy'

So if you have an database table 'addresses' in this structure:

CREATE TABLE addresses (
  id int(11) NOT NULL,
  street varchar(64) DEFAULT NULL,  /* The name of the street. */
  streetnumber varchar(5) DEFAULT NULL,  /* The streetnumber. */
  address_comment varchar(100) DEFAULT NULL,  /* The address comment. */
  latitude decimal(7,7) DEFAULT NULL,  /* The latitude from the address. */
  longitude decimal(7,7) DEFAULT NULL,  /* The longitude from the address. */
  geohash varchar(12) DEFAULT NULL,  /* The geohash from this address. */
) ;

you can search in the table 'addresses' with this select statement:

SELECT * FROM addresses 
WHERE LEFT(geohash,7) IN 
('u1x0esy', 'u1x0esz', 'u1x0etp', 'u1x0etn', 'u1x0etj', 'u1x0esv', 'u1x0est', 'u1x0esw, 'u1x0esx');

This statement gives all addresses that match with the given geohash codes in the 'in clause'.

Note

If you use the new jgeohash version 2.x.x you have to use the new class GeoHashExtensions instead of GeoHashUtils.