com.tomtom.speedtools.geometry

Class GeoHash

java.lang.Object

com.tomtom.speedtools.geometry.GeoHash

public final class GeoHash
extends Object

This class deals with GeoHash functionality. Base source taken from LBS team (thanks Eric Bowman). See http://en.wikipedia.org/wiki/Geohash and http://geospatialweb.googlecode.com.

Constructor Summary

Constructors

Constructor and Description
GeoHash(GeoPoint point) Create a GeoHash from a point.
GeoHash(String hash) Create a GeoHash from a hash string.

Method Summary

Modifier and Type	Method and Description
boolean	canEqual(Object obj) Detects whether an object can be compared to this instance.
boolean	contains(GeoHash other) Specifies whether a GeoHash is contained within this one.
static GeoPoint	decode(String hash) Decodes a geoHash string into a GeoPoint.
GeoHash	decreaseResolution() Shortens the size of the GeoHash by one character, effectively decreasing the resolution.
GeoHash	decreaseResolution(int amount) Shortens the size of the GeoHash, so removes characters from the right, effectively decreasing the resolution.
static String	encode(double lat, double lon)
static String	encode(GeoPoint point) Encodes a GeoPoint into a geoHash string.
boolean	equals(Object obj) Detects whether a given object is equal to this instance.
String	getHash() Return the geo hash string of this object.
GeoPoint	getPoint() Return the point (coordinate) of this geo hash.
int	hashCode() Returns the hashCode of this instance.
static boolean	isValid(String hash) Return whether a hash is a valid Geo Hash.
int	length() Gets the hash length.
GeoHash	moveTo(GeoPoint point) Creates a new GeoHash using the same resolution (length) as the current object to contain a new point.
GeoHash	setResolution(int length) Shortens the size of the GeoHash by an absolute value, so removes characters from the right.
String	toString() Converts the instance to a JSON encoded string.
GeoHash	useResolution(GeoHash other) Returns a new GeoHash object with the same resolution as the specified object.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

GeoHash

public GeoHash(@Nonnull
               String hash)
        throws IllegalArgumentException

Create a GeoHash from a hash string.

Parameters:

hash - Geo hash string.

Throws:

IllegalArgumentException

GeoHash

public GeoHash(@Nonnull
               GeoPoint point)

Create a GeoHash from a point.

Parameters:

point - GeoPoint.

Method Detail

getHash

@Nonnull
public String getHash()

Return the geo hash string of this object. This is not the same as the hashCode.

Returns:

Geo hash string.

getPoint

@Nonnull
public GeoPoint getPoint()

Return the point (coordinate) of this geo hash.

Returns:

GeoPoint coordinate.

moveTo

@Nonnull
public GeoHash moveTo(@Nonnull
                               GeoPoint point)

Creates a new GeoHash using the same resolution (length) as the current object to contain a new point. This method essentially moves the GeoHash rectangle around if needed.

Parameters:

point - Point to be contained by new object.

Returns:

New GeoHash with same resolution that contains the specified point.

useResolution

@Nonnull
public GeoHash useResolution(@Nonnull
                                      GeoHash other)

Returns a new GeoHash object with the same resolution as the specified object.

Parameters:

other - GeoHash object that specifies the resolution.

Returns:

New GeoHash object with same resolution.

decreaseResolution

@Nullable
public GeoHash decreaseResolution()

Shortens the size of the GeoHash by one character, effectively decreasing the resolution.

Returns:

GeoHash with one character removed from the right. May be null.

decreaseResolution

@Nullable
public GeoHash decreaseResolution(int amount)

Shortens the size of the GeoHash, so removes characters from the right, effectively decreasing the resolution.

Parameters:

amount - The amount of characters to remove, must be 0 or bigger.

Returns:

GeoHash with characters removed from the right. May be null.

setResolution

@Nullable
public GeoHash setResolution(int length)

Shortens the size of the GeoHash by an absolute value, so removes characters from the right.

Parameters:

length - The new size of the GeoHash, must be > 0.

Returns:

GeoHash with characters removed from the right.

contains

public boolean contains(@Nonnull
                        GeoHash other)

Specifies whether a GeoHash is contained within this one. Note that a GeoHash always contains itself.

Parameters:

other - Other GeoHash.

Returns:

True if this GeoHash contains the other one.

length

public int length()

Gets the hash length.

Returns:

The length in number of characters.

encode

@Nonnull
public static String encode(@Nonnull
                                     GeoPoint point)

Encodes a GeoPoint into a geoHash string.

Parameters:

point - GeoPoint to be encoded.

Returns:

The created String.

encode

@Nonnull
public static String encode(double lat,
                                     double lon)

decode

@Nonnull
public static GeoPoint decode(@Nonnull
                                       String hash)
                                throws IllegalArgumentException

Decodes a geoHash string into a GeoPoint.

Parameters:

hash - String representation of a GeoHash.

Returns:

The created GeoPoint.

Throws:

IllegalArgumentException - when an invalid hash was given.

isValid

public static boolean isValid(@Nullable
                              String hash)

Return whether a hash is a valid Geo Hash.

Parameters:

hash - String representation of GeoHash.

Returns:

True if this is a valid GeoHash.

canEqual

public boolean canEqual(@Nonnull
                        Object obj)

Detects whether an object can be compared to this instance.

Parameters:

obj - The Object to be tested.

Returns:

True if obj is a GeoHash instance.

toString

@Nonnull
public String toString()

Converts the instance to a JSON encoded string.

Overrides:

toString in class Object

Returns:

The created string.

equals

public boolean equals(@Nullable
                      Object obj)

Detects whether a given object is equal to this instance.

Overrides:

equals in class Object

Parameters:

obj - The object to be tested.

Returns:

True if obj is equal to this instance.

hashCode

public int hashCode()

Returns the hashCode of this instance.

Overrides:

hashCode in class Object

Returns:

The int value of the hasCode.