javax.microedition.location
Class Location

java.lang.Object
  javax.microedition.location.Location

public class Location
extends Object

The Location class represents the standard set of basic location information. This includes the timestamped coordinates, accuracy, speed, course, and information about the positioning method used for the location, plus an optional textual address.

The location method is indicated using a bit field. The individual bits are defined using constants in this class. This bit field is a bitwise combination of the location method technology bits (MTE_*), method type (MTY_*) and method assistance information (MTA_*). All other bits in the 32 bit integer than those that have defined constants in this class are reserved and MUST not be set by implementations (i.e. these bits must be 0).

A Location object may be either 'valid' or 'invalid'. The validity can be queried using the isValid method. A valid Location object represents a location with valid coordinates and the getQualifiedCoordinates method must return there coordinates. An invalid Location object doesn't have valid coordinates, but the extra info that is obtained from the getExtraInfo method can provide information about the reason why it was not possible to provide a valid Location. For an invalid Location object, the getQualifiedCoordinates method may return either null or some coordinates where the information is not necessarily fully correct. The periodic location updates to the LocationListener may return invalid Location objects if it isn't possible to determine the location.

This class is only a container for the information. When the platform implementation returns Location objects, it MUST ensure that it only returns objects where the parameters have values set as described for their semantics in this class.

Field Summary

static int	MTA_ASSISTED Location method is assisted by the other party (Terminal assisted for Network based, Network assisted for terminal based).
static int	MTA_UNASSISTED Location method is unassisted.
static int	MTE_ANGLEOFARRIVAL Location method Angle of Arrival for cellular / terrestrial RF system.
static int	MTE_CELLID Location method Cell-ID for cellular (in GSM, this is the same as CGI, Cell Global Identity).
static int	MTE_SATELLITE Location method using satellites (for example, Global Positioning System (GPS)).
static int	MTE_SHORTRANGE Location method Short-range positioning system (for example, Bluetooth LP).
static int	MTE_TIMEDIFFERENCE Location method Time Difference for cellular / terrestrial RF system (for example, Enhanced Observed Time Difference (E-OTD) for GSM).
static int	MTE_TIMEOFARRIVAL Location method Time of Arrival (TOA) for cellular / terrestrial RF system.
static int	MTY_NETWORKBASED Location method is of type network based.
static int	MTY_TERMINALBASED Location method is of type terminal based.

Constructor Summary

protected

Location(QualifiedCoordinates coords, float speed, float course, long timeStamp, int locationMethod, String extraInfo) A protected constructor for the Location to allow implementations of LocationProviders to construct the Location instances.

Method Summary

AddressInfo	getAddressInfo() Returns the AddressInfo associated with this Location object.
float	getCourse() Returns the terminal's course made good in degrees relative to true north.
String	getExtraInfo(String mimetype) This method is not implemented by leJOS and returns null every time.
int	getLocationMethod() Returns information about the location method used.
QualifiedCoordinates	getQualifiedCoordinates() Returns the coordinates of this location and their accuracy.
float	getSpeed() Returns the terminal's current ground speed in meters per second (m/s) at the time of measurement.
long	getTimestamp() Returns the time stamp at which the data was collected.
boolean	isValid() Returns whether this Location instance represents a valid location with coordinates or an invalid one where all the data, especially the latitude and longitude coordinates, may not be present.
protected void	setCourse(float course) Sets the terminal's course, ensuring that the value is always in the range [0.0,360.0) degrees.
protected void	setSpeed(float speed) Set the current ground speed of the location object in m/s.

Methods inherited from class java.lang.Object

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

Field Detail

MTA_ASSISTED

public static final int MTA_ASSISTED

Location method is assisted by the other party (Terminal assisted for Network based, Network assisted for terminal based). MTA_ASSISTED = 0x00040000

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Constant Field Values

MTA_UNASSISTED

public static final int MTA_UNASSISTED

Location method is unassisted. This bit and MTA_ASSISTED bit MUST NOT both be set. Only one of these bits may be set or neither to indicate that the assistance information is not known. MTA_UNASSISTED = 0x00080000

See Also:

Constant Field Values

MTE_ANGLEOFARRIVAL

public static final int MTE_ANGLEOFARRIVAL

Location method Angle of Arrival for cellular / terrestrial RF system. MTE_ANGLEOFARRIVAL = 0x00000020

See Also:

Constant Field Values

MTE_CELLID

public static final int MTE_CELLID

Location method Cell-ID for cellular (in GSM, this is the same as CGI, Cell Global Identity). MTE_CELLID = 0x00000008

See Also:

Constant Field Values

MTE_SATELLITE

public static final int MTE_SATELLITE

Location method using satellites (for example, Global Positioning System (GPS)). MTE_SATELLITE = 0x00000001

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Constant Field Values

MTE_SHORTRANGE

public static final int MTE_SHORTRANGE

Location method Short-range positioning system (for example, Bluetooth LP). MTE_SHORTRANGE = 0x00000010

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Constant Field Values

MTE_TIMEDIFFERENCE

public static final int MTE_TIMEDIFFERENCE

Location method Time Difference for cellular / terrestrial RF system (for example, Enhanced Observed Time Difference (E-OTD) for GSM). MTE_TIMEDIFFERENCE = 0x00000002

See Also:

Constant Field Values

MTE_TIMEOFARRIVAL

public static final int MTE_TIMEOFARRIVAL

Location method Time of Arrival (TOA) for cellular / terrestrial RF system. MTE_TIMEOFARRIVAL = 0x00000004

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Constant Field Values

MTY_NETWORKBASED

public static final int MTY_NETWORKBASED

Location method is of type network based. This means that the final location result is calculated in the network. This bit and MTY_TERMINALBASED bit MUST NOT both be set. Only one of these bits may be set or neither to indicate that it is not known where the result is calculated. MTY_NETWORKBASED = 0x00020000

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Constant Field Values

MTY_TERMINALBASED

public static final int MTY_TERMINALBASED

Location method is of type terminal based. This means that the final location result is calculated in the terminal. MTY_TERMINALBASED = 0x00010000

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Constant Field Values

Constructor Detail

Location

protected Location(QualifiedCoordinates coords,
                   float speed,
                   float course,
                   long timeStamp,
                   int locationMethod,
                   String extraInfo)

A protected constructor for the Location to allow implementations of LocationProviders to construct the Location instances. This method is not intended to be used by applications.

This constructor sets the fields to implementation specific default values. Location providers are expected to set the fields to the correct values after constructing the object instance.

Throws:

IllegalArgumentException - if the speed is negative if the course is outside 0.0 to 360.0

Method Detail

getAddressInfo

public AddressInfo getAddressInfo()

Returns the AddressInfo associated with this Location object. If no address is available, null is returned. In leJOS this currently always returns null.

Returns:

an AddressInfo associated with this Location object

getCourse

public float getCourse()

Returns the terminal's course made good in degrees relative to true north. The value is always in the range [0.0,360.0) degrees.

Returns:

the terminal's course made good in degrees relative to true north or Float.NaN if the course is not known

getExtraInfo

public String getExtraInfo(String mimetype)

This method is not implemented by leJOS and returns null every time.

Parameters:

mimetype - This variable is ignored by leJOS NXJ. You can submit null.

Returns:

Nothing.

getLocationMethod

public int getLocationMethod()

Returns information about the location method used. The returned value is a bitwise combination (OR) of the method technology, method type and assistance information. The method technology values are defined as constant values named MTE_* in this class, the method type values are named MTY_* and assistance information values are named MTA_*. For example, if the location method used is terminal based, network assisted E-OTD, the value 0x00050002 ( = MTY_TERMINALBASED | MTA_ASSISTED | MTE_TIMEDIFFERENCE) would be returned.

If the location is determined by combining several location technologies, the returned value may have several MTE_* bits set.

If the used location method is unknown, the returned value must have all the bits set to zero.

Only bits that have defined constants within this class are allowed to be used. Other bits are reserved and must be set to 0.

Returns:

a bitfield identifying the used location method

getQualifiedCoordinates

public QualifiedCoordinates getQualifiedCoordinates()

Returns the coordinates of this location and their accuracy.

Returns:

a QualifiedCoordinates object. If the coordinates are not known, returns null.

getSpeed

public float getSpeed()

Returns the terminal's current ground speed in meters per second (m/s) at the time of measurement. The speed is always a non-negative value. Note that unlike the coordinates, speed does not have an associated accuracy because the methods used to determine the speed typically are not able to indicate the accuracy.

Returns:

the current ground speed in m/s for the terminal or Float.NaN if the speed is not known

getTimestamp

public long getTimestamp()

Returns the time stamp at which the data was collected. This timestamp should represent the point in time when the measurements were made. Implementations make best effort to set the timestamp as close to this point in time as possible. The time returned is the time of the local clock in the terminal in milliseconds using the same clock and same time representation as System.currentTimeMillis().

Returns:

a timestamp representing the time

isValid

public boolean isValid()

Returns whether this Location instance represents a valid location with coordinates or an invalid one where all the data, especially the latitude and longitude coordinates, may not be present. A valid Location object contains valid coordinates whereas an invalid Location object may not contain valid coordinates but may contain other information via the getExtraInfo() method to provide information on why it was not possible to provide a valid Location object.

Returns:

a boolean value with true indicating that this Location instance is valid and false indicating an invalid Location instance

See Also:

getExtraInfo(String)

setCourse

protected void setCourse(float course)
                  throws IllegalArgumentException

Sets the terminal's course, ensuring that the value is always in the range [0.0,360.0) degrees.

Parameters:

course - the course to set.

Throws:

IllegalArgumentException - if the course is outside the range.

setSpeed

protected void setSpeed(float speed)
                 throws IllegalArgumentException

Set the current ground speed of the location object in m/s.

Parameters:

speed - must be non-negative or Float.NaN if unknown.

Throws:

IllegalArgumentException - if the speed is negative