javax.microedition.location
Class Coordinates

java.lang.Object
  javax.microedition.location.Coordinates

Direct Known Subclasses:

QualifiedCoordinates

public class Coordinates
extends java.lang.Object

The Coordinates class represents coordinates as latitude-longitude-altitude values. The latitude and longitude values are expressed in degrees using floating point values. The degrees are in decimal values (rather than minutes/seconds). The coordinates are given using the WGS84 datum.

This class also provides convenience methods for converting between a String coordinate representation and the double representation used in this class.

Field Summary

static int	DD_MM Identifier for String coordinate representation Degrees, Minutes, decimal fractions of a minute.
static int	DD_MM_SS Identifier for String coordinate representation Degrees, Minutes, Seconds and decimal fractions of a second.

Constructor Summary

Coordinates(double latitude, double longitude, float altitude)
Constructs a new Coordinates object with the values specified.

Method Summary

float	azimuthTo(Coordinates to) Calculates the azimuth between the two points according to the ellipsoid model of WGS84.
static java.lang.String	convert(double coordinate, int outputType) Converts a double representation of a coordinate with decimal degrees into a String representation.
static double	convert(java.lang.String coordinate) Converts a String representation of a coordinate into the double representation as used in this API.
float	distance(Coordinates to) Calculates the geodetic distance between the two points according to the ellipsoid model of WGS84.
boolean	equals(java.lang.Object obj) Overriding the equals method in Object class to compare the equality of values in two Coordinates objects.
float	getAltitude() Returns the altitude component of this coordinate.
double	getLatitude() Returns the latitude component of this coordinate.
double	getLongitude() Returns the longitude component of this coordinate.
int	hashCode() Overriding the hashCode method in Object class.
void	setAltitude(float altitude) Sets the geodetic altitude for this point.
void	setLatitude(double latitude) Sets the geodetic latitude for this point.
void	setLongitude(double longitude) Sets the geodetic longitude for this point.

Methods inherited from class java.lang.Object

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

Field Detail

DD_MM_SS

public static final int DD_MM_SS

Identifier for String coordinate representation Degrees, Minutes, Seconds and decimal fractions of a second.

See Also:

Constant Field Values

DD_MM

public static final int DD_MM

Identifier for String coordinate representation Degrees, Minutes, decimal fractions of a minute.

See Also:

Constant Field Values

Constructor Detail

Coordinates

public Coordinates(double latitude,
                   double longitude,
                   float altitude)

Constructs a new Coordinates object with the values specified. The latitude and longitude parameters are expressed in degrees using floating point values. The degrees are in decimal values (rather than minutes/seconds).

The coordinate values always apply to the WGS84 datum.

The Float.NaN value can be used for altitude to indicate that altitude is not known.

Parameters:

latitude - The latitude of the location. Valid range: [-90.0, 90.0]. Positive values indicate northern latitude and negative values southern latitude.

longitude - The longitude of the location. Valid range: [-180.0, 180.0]. Positive values indicate eastern longitude and negative values western longitude.

altitude - The altitude of the location in meters, defined as height above the WGS84 ellipsoid. Float.NaN can be used to indicate that altitude is not known.

Throws:

java.lang.IllegalArgumentException - if an input parameter is out of the valid range

Method Detail

getLatitude

public double getLatitude()

Returns the latitude component of this coordinate. Positive values indicate northern latitude and negative values southern latitude.

The latitude is given in WGS84 datum.

Returns:

the latitude in degrees

See Also:

setLatitude(double)

getLongitude

public double getLongitude()

Returns the longitude component of this coordinate. Positive values indicate eastern longitude and negative values western longitude.

The longitude is given in WGS84 datum.

Returns:

the longitude in degrees

See Also:

setLongitude(double)

getAltitude

public float getAltitude()

Returns the altitude component of this coordinate. Altitude is defined to mean height above the WGS84 reference ellipsoid. 0.0 means a location at the ellipsoid surface, negative values mean the location is below the ellipsoid surface, Float.NaN that the altitude is not available.

Returns:

the altitude in meters above the reference ellipsoid

See Also:

setAltitude(float)

setAltitude

public void setAltitude(float altitude)

Sets the geodetic altitude for this point.

Parameters:

altitude - The altitude of the location in meters, defined as height above the WGS84 ellipsoid. 0.0 means a location at the ellipsoid surface, negative values mean the location is below the ellipsoid surface, Float.NaN that the altitude is not available

See Also:

getAltitude()

setLatitude

public void setLatitude(double latitude)

Sets the geodetic latitude for this point. Latitude is given as a double expressing the latitude in degrees in the WGS84 datum.

Parameters:

latitude - the latitude component of this location in degrees, valid range: [-90.0, 90.0]

Throws:

java.lang.IllegalArgumentException - if latitude is out of the valid range

See Also:

getLatitude()

setLongitude

public void setLongitude(double longitude)

Sets the geodetic longitude for this point. Longitude is given as a double expressing the longitude in degrees in the WGS84 datum.

Parameters:

longitude - the longitude of the location in degrees, valid range: [-180.0, 180.0]

Throws:

java.lang.IllegalArgumentException - if longitude is out of the valid range

See Also:

getLongitude()

convert

public static double convert(java.lang.String coordinate)

Converts a String representation of a coordinate into the double representation as used in this API.

There are two string syntaxes supported:

1. Degrees, minutes, seconds and decimal fractions of seconds. This is expressed as a String complying with the following EBNF definition where the degrees are within the range [-179, 179] and the minutes and seconds are within the range [0, 59], or the degrees is -180 or 180 and the minutes, seconds and decimal fractions are 0:

 
    coordinate   = degrees ":" minutes ":" seconds "." decimalfrac | 
                   degrees ":" minutes ":" seconds |
                   degrees ":" minutes
    degrees      = degreedigits | "-" degreedigits
    degreedigits = digit | nonzerodigit digit | "1" digit digit 
    minutes      = minsecfirstdigit digit
    seconds      = minsecfirstdigit digit
    decimalfrac  = 1*3digit 
    digit        = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" |"9"
    nonzerodigit = "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
    minsecfirstdigit = "0" | "1" | "2" | "3" | "4" | "5" 
 

2. Degrees, minutes and decimal fractions of minutes. This is expressed as a String complying with the following EBNF definition where the degrees are within the range [-179, 179] and the minutes are within the range [0, 59], or the degrees is -180 or 180 and the minutes and decimal fractions are 0:

 
    coordinate   = degrees ":" minutes "." decimalfrac |
                   degrees ":" minutes
    degrees      = degreedigits | "-" degreedigits
    degreedigits = digit | nonzerodigit digit | "1" digit digit 
    minutes      = minsecfirstdigit digit
    decimalfrac  = 1*5digit
    digit        = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" |"9"
    nonzerodigit = "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
    minsecfirstdigit = "0" | "1" | "2" | "3" | "4" | "5" 
 

For example, for the double value of the coordinate 61.51d, the corresponding syntax 1 String is "61:30:36" and the corresponding syntax 2 String is "61:30.6".

Parameters:

coordinate - a String in either of the two representation specified above

Returns:

a double value with decimal degrees that matches the String representation given as the parameter

Throws:

java.lang.IllegalArgumentException - if the coordinate input parameter does not comply with the defined syntax for the specified types

java.lang.NullPointerException - if coordinate is null

convert

public static java.lang.String convert(double coordinate,
                                       int outputType)

Converts a double representation of a coordinate with decimal degrees into a String representation.

There are String syntaxes supported are the same as for the convert(String) method. The implementation shall provide as many significant digits for the decimal fractions as are allowed by the String syntax definition.

Parameters:

coordinate - a double representation of a coordinate

outputType - Identifier of the type of the String representation wanted for output. The constant DD_MM_SS identifies the syntax 1 and the constant DD_MM identifies the syntax 2.

Returns:

a String representation of the coordinate in a representation indicated by the parameter

Throws:

java.lang.IllegalArgumentException - if the outputType is not one of the two constant values defined in this class or if the coordinate value is not within the range [-180.0, 180.0] or is Double.NaN

See Also:

convert(String)

azimuthTo

public float azimuthTo(Coordinates to)

Calculates the azimuth between the two points according to the ellipsoid model of WGS84. The azimuth is relative to true north. The Coordinates object on which this method is called is considered the origin for the calculation and the Coordinates object passed as a parameter is the destination which the azimuth is calculated to. When the origin is the North pole and the destination is not the North pole, this method returns 180.0. When the origin is the South pole and the destination is not the South pole, this method returns 0.0. If the origin is equal to the destination, this method returns 0.0. The implementation shall calculate the result as exactly as it can. However, it is required that the result is within 1 degree of the correct result.

Parameters:

to - the Coordinates of the destination

Returns:

The azimuth to the destination in degrees. Result is within the range [0.0 ,360.0).

Throws:

java.lang.NullPointerException - if the parameter to is null

distance

public float distance(Coordinates to)

Calculates the geodetic distance between the two points according to the ellipsoid model of WGS84. Altitude is neglected from calculations.

The implementation shall calculate this as exactly as it can. However, it is required that the result is within 0.36% of the correct result.

Parameters:

to - the Coordinates of the destination

Returns:

the distance to the destination in meters

Throws:

java.lang.NullPointerException - if the parameter to is null

equals

public boolean equals(java.lang.Object obj)

Overriding the equals method in Object class to compare the equality of values in two Coordinates objects. Since longitudes values -180 and 180 denote the same longitude, they must be considered equal.

Overrides:

equals in class java.lang.Object

Parameters:

obj - object to which the comparison is done

Returns:

true if all fields in the objects are equal, else false

hashCode

public int hashCode()

Overriding the hashCode method in Object class. The method returns a hash code value for the coordinates object. Two Coordinates objects that are equal must have the same hash code. For more information see java.lang.Object.hashCode() method.

Overrides:

hashCode in class java.lang.Object

Returns:

the hash code of the coordinates