Package org.apache.sis.measure
Class Angle
java.lang.Object
org.apache.sis.measure.Angle
- All Implemented Interfaces:
Serializable
,Comparable<Angle>
,Formattable
- Direct Known Subclasses:
ElevationAngle
,Latitude
,Longitude
An angle in decimal degrees. An angle is the amount of rotation needed to bring one line or plane
into coincidence with another. Various kind of angles are used in geographic information systems,
some of them having a specialized class in Apache SIS:
- Latitude is an angle ranging from 0° at the equator to 90° at the poles.
- Longitude is an angle measured east-west from a prime meridian (usually Greenwich, but not necessarily).
- Azimuth is a direction given by an angle between 0° and 360° measured clockwise from North.
- Bearing is a direction given by an angle between 0° and 90° in a quadrant defined by a cardinal direction.
- Bearing is also sometimes used in navigation for an angle relative to the vessel forward direction.
- Deflection angle is the angle between a line and the prolongation of a preceding line.
- Interior angle is an angle measured between two lines of sight.
- Elevation angle is the angular height from the horizontal plane to an object above the horizon.
Formatting angles
The recommended way to format angles is to instantiate anAngleFormat
once, then to
reuse it many times. As a convenience, Angle
objects can also be formatted by the
"%s"
conversion specifier of Formatter
, but this is less efficient for this
class.
Immutability and thread safety
This class and theLatitude
/ Longitude
subclasses are immutable, and thus
inherently thread-safe. Other subclasses may or may not be immutable, at implementation choice
(see Number
for an example of a similar in purpose class having mutable subclasses).- Since:
- 0.3
- Version:
- 0.8
- See Also:
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate static Format
A shared instance ofAngleFormat
.private static final long
Serial number for inter-operability with different versions.private final double
Angle value in decimal degrees. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
Compares twoAngle
objects numerically.double
degrees()
Returns the angle value in decimal degrees.boolean
Compares the specified object with this angle for equality.void
Formats this angle using the provider formatter.private static Format
Returns a shared instance ofAngleFormat
.int
hashCode()
Returns a hash code for thisAngle
object.(package private) char
hemisphere
(boolean negative) Returns the hemisphere character for an angle of the given sign.(package private) double
maximum()
Upper threshold before to format an angle as an ordinary number.double
radians()
Returns the angle value in radians.toString()
Returns a string representation of thisAngle
object.(package private) static double
valueOf
(org.opengis.geometry.DirectPosition position, org.opengis.referencing.cs.AxisDirection positive, org.opengis.referencing.cs.AxisDirection negative) Returns the angular value of the axis having the given direction.
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Field Details
-
serialVersionUID
private static final long serialVersionUIDSerial number for inter-operability with different versions.- See Also:
-
format
A shared instance ofAngleFormat
.- See Also:
-
θ
private final double θAngle value in decimal degrees. We use decimal degrees as the storage unit instead of radians in order to avoid rounding errors, since there is no way to represent 30°, 45°, 90°, 180°, etc. in radians without errors.
-
-
Constructor Details
-
Angle
public Angle(double θ) Constructs a new angle with the specified value in decimal degrees.- Parameters:
\u03b8
- angle in decimal degrees.
-
Angle
Constructs a newly allocatedAngle
object that contain the angular value represented by the string. The string should represent an angle in either fractional degrees (e.g. 45.5°) or degrees with minutes and seconds (e.g. 45°30').This is a convenience constructor mostly for testing purpose, since it uses a fixed locale. Developers should consider using
AngleFormat
for end-user applications instead of this constructor.- Parameters:
text
- a string to be converted to anAngle
.- Throws:
NumberFormatException
- if the string does not contain a parsable angle.- See Also:
-
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Method Details
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valueOf
static double valueOf(org.opengis.geometry.DirectPosition position, org.opengis.referencing.cs.AxisDirection positive, org.opengis.referencing.cs.AxisDirection negative) Returns the angular value of the axis having the given direction. This helper method is used for subclass constructors expecting aDirectPosition
argument.- Parameters:
position
- the position from which to get an angular value.positive
- axis direction of positive values.negative
- axis direction of negative values.- Returns:
- angular value in degrees.
- Throws:
IllegalArgumentException
- if the given coordinate it not associated to a CRS, or if no axis oriented toward the given directions is found, or if that axis does not use angular units.
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degrees
public double degrees()Returns the angle value in decimal degrees.- Returns:
- the angle value in decimal degrees.
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radians
public double radians()Returns the angle value in radians.- Returns:
- the angle value in radians.
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hashCode
public int hashCode()Returns a hash code for thisAngle
object. -
equals
Compares the specified object with this angle for equality. -
compareTo
Compares twoAngle
objects numerically. The comparison is done as if by theDouble.compare(double, double)
method.- Specified by:
compareTo
in interfaceComparable<Angle>
- Parameters:
that
- the angle to compare with this object for order.- Returns:
- -1 if this angle is smaller than the given one, +1 if greater or 0 if equals.
-
maximum
double maximum()Upper threshold before to format an angle as an ordinary number. This is set to 90° in the case of latitude numbers. -
hemisphere
char hemisphere(boolean negative) Returns the hemisphere character for an angle of the given sign. This is used only bytoString()
, not byAngleFormat
. -
toString
Returns a string representation of thisAngle
object. This is a convenience method mostly for debugging purpose, since it uses a fixed locale. Developers should consider usingAngleFormat
for end-user applications instead than this method. -
getAngleFormat
Returns a shared instance ofAngleFormat
. The return type isFormat
in order to avoid class loading before necessary.This method must be invoked in a
synchronized(Angle.class)
block. We use synchronization instead of static class initialization becauseAngleFormat
is not thread-safe, so it needs to be used in a synchronized block anyway. We could avoid synchronization by usingThreadLocal
, but this brings other issues in OSGi context. Given that our Javadoc said thatAngle(String)
andtoString()
should be used mostly for debugging purpose, we consider not worth to ensure high concurrency capability here. -
formatTo
Formats this angle using the provider formatter. This method is invoked when anAngle
object is formatted using the"%s"
conversion specifier ofFormatter
. Users don't need to invoke this method explicitly.Special cases:
- If the precision is 0, then this method formats an empty string.
- If the precision is 1 and this angle is a
Latitude
orLongitude
, then this method formats only the hemisphere symbol. - Otherwise the precision, if positive, is given to
AngleFormat.setMaximumWidth(int)
.
- Specified by:
formatTo
in interfaceFormattable
- Parameters:
formatter
- the formatter in which to format this angle.flags
-FormattableFlags.LEFT_JUSTIFY
for left alignment, or 0 for right alignment.width
- minimal number of characters to write, padding with' '
if necessary.precision
- maximal number of characters to write, or -1 if no limit.
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