galileo.util

Class GeoHash

java.lang.Object

galileo.util.GeoHash

public class GeoHash
extends java.lang.Object

This class provides an implementation of the GeoHash (http://www.geohash.org) algorithm. See http://en.wikipedia.org/wiki/Geohash for implementation details.

Author:

malensek

Field Summary

Fields

Modifier and Type	Field and Description
static byte	BITS_PER_CHAR
static java.util.HashMap<java.lang.Character,java.lang.Integer>	charLookupTable Allows lookups from a GeoHash character to its integer index value.
static char[]	charMap This character array maps integer values (array indices) to their GeoHash base32 alphabet equivalents.
static int	LATITUDE_RANGE
static int	LONGITUDE_RANGE

Constructor Summary

Constructors

Constructor and Description
GeoHash()

Method Summary

Modifier and Type	Method and Description
static SpatialRange	decodeHash(java.lang.String geoHash) Decode a GeoHash to an approximate bounding box that contains the original GeoHashed point.
static java.lang.String	encode(Coordinates coords, int precision) Encode a set of Coordinates into a GeoHash string.
static java.lang.String	encode(float latitude, float longitude, int precision) Encode latitude and longitude into a GeoHash string.
static java.lang.String	encode(SpatialRange range, int precision) Encode SpatialRange into a GeoHash string.
static long	hashToLong(java.lang.String hash) Convert a GeoHash String to a long integer.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BITS_PER_CHAR

public static final byte BITS_PER_CHAR

See Also:

Constant Field Values

LATITUDE_RANGE

public static final int LATITUDE_RANGE

See Also:

Constant Field Values

LONGITUDE_RANGE

public static final int LONGITUDE_RANGE

See Also:

Constant Field Values

charMap

public static final char[] charMap

This character array maps integer values (array indices) to their GeoHash base32 alphabet equivalents.

charLookupTable

public static final java.util.HashMap<java.lang.Character,java.lang.Integer> charLookupTable

Allows lookups from a GeoHash character to its integer index value.

Constructor Detail

GeoHash

public GeoHash()

Method Detail

encode

public static java.lang.String encode(Coordinates coords,
                                      int precision)

Encode a set of Coordinates into a GeoHash string.

Parameters:

coords - Coordinates to get GeoHash for.

precision - Desired number of characters in the returned GeoHash String. More characters means more precision.

Returns:

GeoHash string.

encode

public static java.lang.String encode(SpatialRange range,
                                      int precision)

Encode SpatialRange into a GeoHash string.

Parameters:

range - SpatialRange to get GeoHash for.

precision - Number of characters in the returned GeoHash String. More characters is more precise.

Returns:

GeoHash string.

encode

public static java.lang.String encode(float latitude,
                                      float longitude,
                                      int precision)

Encode latitude and longitude into a GeoHash string.

Parameters:

latitude - Latitude coordinate, in degrees.

longitude - Longitude coordinate, in degrees.

precision - Number of characters in the returned GeoHash String. More characters is more precise.

Returns:

resulting GeoHash String.

hashToLong

public static long hashToLong(java.lang.String hash)

Convert a GeoHash String to a long integer.

Parameters:

hash - GeoHash String to convert.

Returns:

The GeoHash as a long integer.

decodeHash

public static SpatialRange decodeHash(java.lang.String geoHash)

Decode a GeoHash to an approximate bounding box that contains the original GeoHashed point.

Parameters:

geoHash - GeoHash string

Returns:

Spatial Range (bounding box) of the GeoHash.