Module org.apache.sis.referencing

Package org.apache.sis.parameter

Class Parameters

Object

Parameters

All Implemented Interfaces:

Cloneable, General­Parameter­Value, Parameter­Value­Group

Direct Known Subclasses:

Contextual­Parameters, Default­Parameter­Value­Group

public abstract class Parameters
extends Object
implements ParameterValueGroup, Cloneable

Convenience methods for fetching parameter values despite the variations in parameter names, value types and units. See Default­Parameter­Value­Group javadoc for a description of the standard way to get and set a particular parameter in a group. The remaining of this javadoc is specific to Apache SIS.

Convenience methods

This class provides the following convenience static methods:

• cast(…, Class) for type safety with parameterized types.
• get­Member­Name(Parameter­Descriptor) for inter-operability between ISO 19111 and ISO 19115.
• get­Value­Domain(Parameter­Descriptor) for information purpose.
• copy(Parameter­Value­Group, Parameter­Value­Group) for copying values into an existing instance.

Most instance methods in this class follow the same naming pattern than the methods provided by the Parameter­Value interface. Those methods are themselves inspired by JDK methods:

Methods fetching parameter value

Parameters method	ParameterValue method	JDK methods
getValue(ParameterDescriptor)	getValue()
booleanValue(ParameterDescriptor)	booleanValue()	Boolean.booleanValue()
intValue(ParameterDescriptor)	intValue()	Number.intValue()
intValueList(ParameterDescriptor)	intValueList()
doubleValue(ParameterDescriptor)	doubleValue()	Number.doubleValue()
doubleValueList(ParameterDescriptor)	doubleValueList()
stringValue(ParameterDescriptor)	stringValue()

Fetching parameter values despite different names, types or units

The common way to get a parameter is to invoke the Parameter­Value­Group.parameter(String) method. This Parameters class provides alternative ways, using a Parameter­Descriptor argument instead of a String argument. Those descriptors provide additional information like the various aliases under which the same parameter may be known. By using this information, Parameters can choose the most appropriate parameter name or alias (by searching for a common authority) when it delegates its work to the parameter(String) method.

Example

The same parameter may be known under different names. For example, the length of the semi-major axis of the ellipsoid is commonly known as "semi_major". But that parameter can also be named "semi_major_axis", "earth_radius" or simply "a" in other libraries. When fetching parameter values, we do not always know in advance which of the above-cited names is recognized by an arbitrary Parameter­Value­Group instance.

Parameters uses also the descriptor information for applying type and unit conversions (i.e. returned values are converted to the units of measurement specified by the given parameter descriptor).

Note for subclass implementers

This class does not implement any method from the Parameter­Value­Group interface (this class is not named “Abstract­Parameter­Value­Group” for that reason). Extending this class or extending Object make almost no difference for implementers; Parameters purpose is mostly to extend the API for users convenience. All methods in this class get their information from the Parameter­Value­Group methods. In addition, unless otherwise specified, methods in this class is isolated from all others: overriding one method has no impact on other methods.

Since:

0.4

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Parameters()	For subclass constructors only.

Method Summary

Modifier and Type	Method	Description
boolean	boolean­Value(Parameter­Descriptor<Boolean> parameter)	Returns the boolean value of the parameter identified by the given descriptor.
static <T> Parameter­Descriptor<T>	cast(Parameter­Descriptor<?> descriptor, Class<T> value­Class)	Casts the given parameter descriptor to the given type.
static <T> Parameter­Value<T>	cast(Parameter­Value<?> parameter, Class<T> value­Class)	Casts the given parameter value to the given type.
static Parameters	cast­Or­Wrap(Parameter­Value­Group parameters)	Returns the given parameter value group as a Parameters instance.
Parameters	clone()	Returns a copy of this group of parameter values.
static void	copy(Parameter­Value­Group values, Parameter­Value­Group destination)	Copies the values of a parameter group into another parameter group.
double	double­Value(Parameter­Descriptor<? extends Number> parameter)	Returns the floating point value of the parameter identified by the given descriptor.
double	double­Value(Parameter­Descriptor<? extends Number> parameter, Unit<?> unit)	Returns the floating point value of the parameter identified by the given descriptor, converted to the given unit of measurement.
double[]	double­Value­List(Parameter­Descriptor<double[]> parameter)	Returns the floating point values of the parameter identified by the given descriptor.
static General­Parameter­Descriptor[]	get­Descriptors(General­Parameter­Value... parameters)	Returns the descriptors of the given parameters, in the same order.
<T> T	get­Mandatory­Value(Parameter­Descriptor<T> parameter)	Returns the value of the parameter identified by the given descriptor, or throws an exception if none.
static Member­Name	get­Member­Name(Parameter­Descriptor<?> parameter)	Gets the parameter name as an instance of Member­Name.
<T> Parameter­Value<T>	get­Or­Create(Parameter­Descriptor<T> parameter)	Returns the parameter identified by the given descriptor.
<T> T	get­Value(Parameter­Descriptor<T> parameter)	Returns the value of the parameter identified by the given descriptor, or null if none.
static Range<?>	get­Value­Domain(Parameter­Descriptor<?> descriptor)	Returns the domain of valid values defined by the given descriptor, or null if none.
int	int­Value(Parameter­Descriptor<? extends Number> parameter)	Returns the integer value of the parameter identified by the given descriptor.
int[]	int­Value­List(Parameter­Descriptor<int[]> parameter)	Returns the integer values of the parameter identified by the given descriptor.
static boolean	is­Unmodifiable(Parameter­Value­Group parameters)	Returns true if the given parameter group is a non-null instance created by unmodifiable(…).
void	print()	Prints a string representation of this group to the standard output stream.
String	string­Value(Parameter­Descriptor<? extends Char­Sequence> parameter)	Returns the string value of the parameter identified by the given descriptor.
String	to­String()	Returns a string representation of this group.
static Parameters	unmodifiable(Parameter­Value­Group parameters)	Returns the given parameter value group as an unmodifiable Parameters instance.
static Parameters	unmodifiable(Parameter­Value­Group parameters, Predicate<? super General­Parameter­Descriptor> filter)	Returns the given parameter value group as an unmodifiable Parameters instance with some parameters hidden.

Methods inherited from class Object

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

Methods inherited from interface ParameterValueGroup

add­Group, get­Descriptor, groups, parameter, values

Constructor Details

Parameters

protected Parameters()

For subclass constructors only.

Method Details

isUnmodifiable

public static boolean isUnmodifiable(ParameterValueGroup parameters)

Returns true if the given parameter group is a non-null instance created by unmodifiable(…).

Parameters:

parameters - the parameter group to test. Can be null.

Returns:

whether the given parameters are non-null and unmodifiable.

Since:

1.3

unmodifiable

public static Parameters unmodifiable(ParameterValueGroup parameters)

Returns the given parameter value group as an unmodifiable Parameters instance. If the given parameters is already an unmodifiable instance of Parameters, then it is returned as-is. Otherwise this method copies all parameter values in a new, unmodifiable, parameter group instance.

Parameters:

parameters - the parameters to make unmodifiable, or null.

Returns:

an unmodifiable group with the same parameters than the given group, or null if the given argument was null.

Since:

0.7

See Also:

• Default­Parameter­Value.unmodifiable(Parameter­Value)

unmodifiable

public static Parameters unmodifiable(ParameterValueGroup parameters,
 Predicate<? super GeneralParameterDescriptor> filter)

Returns the given parameter value group as an unmodifiable Parameters instance with some parameters hidden. The hidden parameters are excluded from the list returned by Parameter­Value­Group.values(), but are otherwise still accessible when the hidden parameters is explicitly named in a call to Parameter­Value­Group.parameter(String).

Use case

This method is used for hiding parameters that should be inferred from the context. For example, the "semi_major" and "semi_minor" parameters are included in the list of Math­Transform parameters because that class has no way to know the values if they are not explicitly provided. But those semi-axis length parameters should not be included in the list of Coordinate­Operation parameters because they are inferred from the context (the source and target CRS).

Parameters:

parameters - the parameters to make unmodifiable, or null.

filter - specifies which source parameters to keep visible, or null if no filtering.

Returns:

an unmodifiable group with the parameters of the given group to keep visible, or null if the parameters argument was null.

Since:

1.3

castOrWrap

public static Parameters castOrWrap(ParameterValueGroup parameters)

Returns the given parameter value group as a Parameters instance. If the given parameters is already an instance of Parameters, then it is returned as-is. Otherwise this method returns a wrapper which delegate all method invocations to the given instance.

This method provides a way to get access to the non-static Parameters methods, like get­Value(Parameter­Descriptor), for an arbitrary Parameter­Value­Group instance.

Parameters:

parameters - the object to cast or wrap, or null.

Returns:

the given argument as an instance of Parameters (may be the same reference), or null if the given argument was null.

cast

public static <T> ParameterDescriptor<T> cast(ParameterDescriptor<?> descriptor,
 Class<T> valueClass)
                                       throws ClassCastException

Casts the given parameter descriptor to the given type. An exception is thrown immediately if the parameter does not have the expected value class.

Type Parameters:

T - the expected value class.

Parameters:

descriptor - the descriptor to cast, or null.

value­Class - the expected value class.

Returns:

the descriptor casted to the given value class, or null if the given descriptor was null.

Throws:

Class­Cast­Exception - if the given descriptor does not have the expected value class.

See Also:

• Class.cast(Object)

cast

public static <T> ParameterValue<T> cast(ParameterValue<?> parameter,
 Class<T> valueClass)
                                  throws ClassCastException

Casts the given parameter value to the given type. An exception is thrown immediately if the parameter does not have the expected value class.

Type Parameters:

T - the expected value class.

Parameters:

parameter - the parameter to cast, or null.

value­Class - the expected value class.

Returns:

the value casted to the given type, or null if the given value was null.

Throws:

Class­Cast­Exception - if the given value doesn't have the expected value class.

See Also:

• Class.cast(Object)

getDescriptors

public static GeneralParameterDescriptor[] getDescriptors(GeneralParameterValue... parameters)

Returns the descriptors of the given parameters, in the same order. Special cases:

• If the given array is null, then this method returns null.
• If an element of the given array is null, then the corresponding element of the returned array is also null.

Parameters:

parameters - the parameter values from which to get the descriptors, or null.

Returns:

the descriptors of the given parameter values, or null if the parameters argument was null.

Since:

0.6

getMemberName

public static MemberName getMemberName(ParameterDescriptor<?> parameter)

Gets the parameter name as an instance of Member­Name. This method performs the following checks:

• If the primary name is an instance of Member­Name (for example a Named­Identifier subclass), returns that primary name.
• Otherwise this method searches for the first alias which is an instance of Member­Name (a subtype of aliases type). If found, that alias is returned.
• If no alias is found, then this method tries to build a Member­Name from the primary name and the value class, using the mapping defined in Default­Type­Name javadoc.

This method can be used as a bridge between the parameter object defined by ISO 19111 (namely CC_Operation­Parameter) and the one defined by ISO 19115 (namely SV_Parameter).

Parameters:

parameter - the parameter from which to get the name (may be null).

Returns:

the member name, or null if none.

Since:

0.5

See Also:

• Names.create­Member­Name(Char­Sequence, String, Char­Sequence, Class)

getValueDomain

public static Range<?> getValueDomain(ParameterDescriptor<?> descriptor)

Returns the domain of valid values defined by the given descriptor, or null if none. This method performs the following operations:

• If the given parameter is an instance of Default­Parameter­Descriptor, delegate to Default­Parameter­Descriptor.get­Value­Domain().
• Otherwise builds the range from the minimum value, maximum value and, if the values are numeric, from the unit.

Parameters:

descriptor - the parameter descriptor, or null.

Returns:

the domain of valid values, or null if none.

See Also:

• Default­Parameter­Descriptor.get­Value­Domain()

getValue

public <T> T getValue(ParameterDescriptor<T> parameter)
               throws ParameterNotFoundException

Returns the value of the parameter identified by the given descriptor, or null if none. This method uses the following information from the given parameter descriptor:

• The most appropriate name or alias to use for searching in this Parameter­Value­Group, chosen as below:
  • a name or alias defined by the same authority, if any;
  • an arbitrary name or alias otherwise.
• The default value to return if there is no value associated to the above-cited name or alias.
• The unit of measurement (if any) of numerical value to return.
• The type of value to return.

This method can be useful when the Parameter­Descriptor are known in advance, for example in the implementation of some coordinate operation method. If the caller has no such Parameter­Descriptor at hand, then the parameter(String) method is probably more convenient.

Type Parameters:

T - the type of the parameter value.

Parameters:

parameter - the name or alias of the parameter to look for, together with the desired type and unit of value.

Returns:

the requested parameter value if it exists, or the default value otherwise (which may be null).

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Unconvertible­Object­Exception - if the parameter value cannot be converted to the expected type.

Since:

0.6

See Also:

• get­Mandatory­Value(Parameter­Descriptor)
• get­Or­Create(Parameter­Descriptor)
• Default­Parameter­Value­Group.parameter(String)
• Default­Parameter­Value.get­Value()

getMandatoryValue

public <T> T getMandatoryValue(ParameterDescriptor<T> parameter)
                        throws ParameterNotFoundException

Returns the value of the parameter identified by the given descriptor, or throws an exception if none. The default implementation performs the same work than get­Value(Parameter­Descriptor) and verifies that the returned value is non-null.

Type Parameters:

T - the type of the parameter value.

Parameters:

parameter - the name or alias of the parameter to look for, together with the desired type and unit of value.

Returns:

the requested parameter value if it exists, or the default value otherwise provided that it is not null.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Illegal­State­Exception - if the value is not defined and there is no default value.

Since:

0.7

See Also:

• get­Value(Parameter­Descriptor)
• get­Or­Create(Parameter­Descriptor)

booleanValue

public boolean booleanValue(ParameterDescriptor<Boolean> parameter)
                     throws ParameterNotFoundException

Returns the boolean value of the parameter identified by the given descriptor. See get­Value(Parameter­Descriptor) for more information about how this method uses the given parameter argument.

Parameters:

parameter - the name or alias of the parameter to look for.

Returns:

the requested parameter value if it exists, or the non-null default value otherwise.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Illegal­State­Exception - if the value is not defined and there is no default value.

Since:

0.6

See Also:

• Default­Parameter­Value.boolean­Value()

intValue

public int intValue(ParameterDescriptor<? extends Number> parameter)
             throws ParameterNotFoundException

Returns the integer value of the parameter identified by the given descriptor. See get­Value(Parameter­Descriptor) for more information about how this method uses the given parameter argument.

Parameters:

parameter - the name or alias of the parameter to look for.

Returns:

the requested parameter value if it exists, or the non-null default value otherwise.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Illegal­State­Exception - if the value is not defined and there is no default value.

Since:

0.6

See Also:

• Default­Parameter­Value.int­Value()

intValueList

public int[] intValueList(ParameterDescriptor<int[]> parameter)
                   throws ParameterNotFoundException

Returns the integer values of the parameter identified by the given descriptor. See get­Value(Parameter­Descriptor) for more information about how this method uses the given parameter argument.

Parameters:

parameter - the name or alias of the parameter to look for.

Returns:

the requested parameter values if they exist, or the non-null default value otherwise.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Illegal­State­Exception - if the value is not defined and there is no default value.

Since:

0.6

See Also:

• Default­Parameter­Value.int­Value­List()

doubleValue

public double doubleValue(ParameterDescriptor<? extends Number> parameter)
                   throws ParameterNotFoundException

Returns the floating point value of the parameter identified by the given descriptor. See get­Value(Parameter­Descriptor) for more information about how this method uses the given parameter argument.

If the given descriptor supplies a unit of measurement, then the returned value will be converted into that unit.

Parameters:

parameter - the name or alias of the parameter to look for.

Returns:

the requested parameter value if it exists, or the non-null default value otherwise.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Illegal­State­Exception - if the value is not defined and there is no default value.

Since:

0.6

See Also:

• Default­Parameter­Value.double­Value(Unit)

doubleValue

public double doubleValue(ParameterDescriptor<? extends Number> parameter,
 Unit<?> unit)
                   throws ParameterNotFoundException

Returns the floating point value of the parameter identified by the given descriptor, converted to the given unit of measurement. See get­Value(Parameter­Descriptor) for more information about how this method uses the given parameter argument.

Parameters:

parameter - the name or alias of the parameter to look for.

unit - the desired unit of measurement.

Returns:

the requested parameter value if it exists, or the non-null default value otherwise.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Illegal­State­Exception - if the value is not defined and there is no default value.

Illegal­Argument­Exception - if the specified unit is invalid for the parameter.

Since:

1.3

See Also:

• Default­Parameter­Value.double­Value(Unit)

doubleValueList

public double[] doubleValueList(ParameterDescriptor<double[]> parameter)
                         throws ParameterNotFoundException

Returns the floating point values of the parameter identified by the given descriptor. See get­Value(Parameter­Descriptor) for more information about how this method uses the given parameter argument.

If the given descriptor supplies a unit of measurement, then the returned values will be converted into that unit.

Parameters:

parameter - the name or alias of the parameter to look for.

Returns:

the requested parameter values if they exists, or the non-null default value otherwise.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Illegal­State­Exception - if the value is not defined and there is no default value.

Since:

0.6

See Also:

• Default­Parameter­Value.double­Value­List(Unit)

stringValue

public String stringValue(ParameterDescriptor<? extends CharSequence> parameter)
                   throws ParameterNotFoundException

Returns the string value of the parameter identified by the given descriptor. See get­Value(Parameter­Descriptor) for more information about how this method uses the given parameter argument.

Parameters:

parameter - the name or alias of the parameter to look for.

Returns:

the requested parameter value if it exists, or the non-null default value otherwise.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Illegal­State­Exception - if the value is not defined and there is no default value.

Since:

0.6

See Also:

• Default­Parameter­Value.string­Value()

getOrCreate

public <T> ParameterValue<T> getOrCreate(ParameterDescriptor<T> parameter)
                                  throws ParameterNotFoundException

Returns the parameter identified by the given descriptor. If the identified parameter is optional and not yet created, then it will be created now.

The default implementation is equivalent to:

return cast(parameter(name), parameter.getValueClass());

where name is a parameter name or alias chosen by the same algorithm than get­Value(Parameter­Descriptor).

Type Parameters:

T - the type of the parameter value.

Parameters:

parameter - the parameter to look for.

Returns:

the requested parameter instance.

Throws:

Parameter­Not­Found­Exception - if the given parameter name or alias is not legal for this group.

Since:

0.6

See Also:

• get­Value(Parameter­Descriptor)
• get­Mandatory­Value(Parameter­Descriptor)
• Default­Parameter­Value­Group.parameter(String)

clone

public Parameters clone()

Returns a copy of this group of parameter values. The default implementation performs a shallow copy, but subclasses are encouraged to perform a deep copy.

Specified by:

clone in interface General­Parameter­Value

Specified by:

clone in interface Parameter­Value­Group

Overrides:

clone in class Object

Returns:

a copy of this group of parameter values.

See Also:

• copy(Parameter­Value­Group, Parameter­Value­Group)

copy

public static void copy(ParameterValueGroup values,
 ParameterValueGroup destination)
                 throws InvalidParameterNameException,
InvalidParameterValueException

Copies the values of a parameter group into another parameter group. All values in the source group shall be valid for the destination group, but the destination may have more parameters. Sub-groups are copied recursively.

A typical usage of this method is for transferring values from an arbitrary implementation to some specific implementation, or to a parameter group using a different but compatible descriptor.

Parameters:

values - the parameter values to copy.

destination - where to copy the values.

Throws:

Invalid­Parameter­Name­Exception - if a source parameter name is unknown to the destination.

Invalid­Parameter­Value­Exception - if the value of a source parameter is invalid for the destination.

Since:

0.5

See Also:

• clone()

toString

public String toString()

Returns a string representation of this group. The default implementation delegates to Parameter­Format.

This method is for information purpose only and may change in future SIS version.

Overrides:

to­String in class Object

Since:

0.7

print

@Debug
public void print()

Prints a string representation of this group to the standard output stream. If a console is attached to the running JVM (i.e. if the application is run from the command-line and the output is not redirected to a file) and if Apache SIS thinks that the console supports the ANSI escape codes (a.k.a. X3.64), then a syntax coloring will be applied.

This is a convenience method for debugging purpose and for console applications.

Since:

0.7