Package org.apache.sis.internal.converter

Class FractionConverter.FromInteger

java.lang.Object
org.apache.sis.internal.converter.FractionConverter.FromInteger
All Implemented Interfaces:
Serializable, Function<Integer,Fraction>, ObjectConverter<Integer,Fraction>
Enclosing class:
FractionConverter
public static final class FractionConverter.FromInteger extends Object
The inverse of FractionConverter.
See Also:

  • Field Details

  • Constructor Details

    • FromInteger

      public FromInteger()
      Creates a new converter. Only one instance is enough, but this constructor needs to be public for allowing invocation by ServiceLoader.

  • Method Details

    • unique

      public ObjectConverter<Integer,Fraction> unique()
      Returns an unique instance of this converter if one exists. If a converter already exists for the same source an target classes, then this converter is returned. Otherwise this converter is returned without being cached.
      Returns:
      the unique instance, or this if no unique instance can be found.
      See Also:
      • SystemConverter.unique()

    • inverse

      public ObjectConverter<Fraction,Integer> inverse()
      Default to non-invertible conversion. Must be overridden by subclasses that support inversions.
      Specified by:
      inverse in interface ObjectConverter<Integer,Fraction>
      Returns:
      a converter for converting instances of T back to instances of S.
      See Also:

    • properties

      public Set<FunctionProperty> properties()
      Description copied from interface: ObjectConverter
      Returns the manner in which source values (S) are mapped to target values (T). Some possible function properties are:
      • Injective if no pair of S can produce the same T value (e.g.: conversions from Integer to String).
      • Surjective if every values of T can be created from one or many values of S (e.g.: conversions from String to Integer).
      • Bijective if there is a one-to-one relationship between the S and T values.
      • Order preserving if any sequence of increasing S values (in the sense of Comparable) is mapped to a sequence of increasing T values.
      • Order reversing if any sequence of increasing S values (in the sense of Comparable) is mapped to a sequence of decreasing T values.
      Note that if the ObjectConverter.apply(Object) method returns null for unconvertible source values, then this properties set cannot contain FunctionProperty.INJECTIVE because more than one source value could be converted to the same null target value.
      Returns:
      the manners in which source values are mapped to target values. May be an empty set, but never null.

    • apply

      public Fraction apply(Integer value)
      Creates a new fraction from the given integer.
      Parameters:
      value - the integer to convert.
      Returns:
      a fraction equals to the given integer.

    • getSourceClass

      public final Class<Integer> getSourceClass()
      Returns the source class given at construction time.
      Specified by:
      getSourceClass in interface ObjectConverter<S,T>
      Returns:
      the type of objects to convert.

    • getTargetClass

      public final Class<Fraction> getTargetClass()
      Returns the target class given at construction time.
      Specified by:
      getTargetClass in interface ObjectConverter<S,T>
      Returns:
      the type of converted objects.

    • equals

      public final boolean equals(Object other)
      Performs the comparisons documented in Object.equals(Object) with an additional check: if both objects to compare are SystemConverter, then also requires the two objects to be of the same class. We do that in order to differentiate the "ordinary" converters from the FallbackConverter.

      Implementation note

      This is admittedly a little bit convolved. A cleaner approach would have been to not allow the ConverterRegister hash map to contain anything else than ClassPair keys, but the current strategy of using the same instance for keys and values reduces a little bit the number of objects to create in the JVM. Another cleaner approach would have been to compare ObjectConverters in a separated method, but users invoking equals on our system converters could be surprised.

      Our equals(Object) definition have the following implications regarding the way to use the ConverterRegistry.converters map:

      • When searching for a converter of the same class than the key (as in the ConverterRegistry.findEquals(SystemConverter) method), then there is no restriction on the key that can be given to the Map.get(K) method. The Map is "normal".
      • When searching for a converter for a pair of source and target classes (as in ConverterRegistry.find(Class, Class)), the key shall be an instance of ClassPair instance (not a subclass).
      Parameters:
      other - the object to compare with this SystemConverter.
      Returns:
      true if the given object is a ClassPair or a converter of the same class than this, and both have the same source and target classes.

    • readResolve

      protected final Object readResolve() throws ObjectStreamException
      Returns the singleton instance on deserialization, if any. If no instance already exist in the virtual machine, we do not cache the instance (for now) for security reasons.
      Returns:
      the object to use after deserialization.
      Throws:
      ObjectStreamException - if the serialized object defines an unknown data type.

    • hashCode

      public final int hashCode()
      Returns a hash code value for this ClassPair. See Object.equals(Object) javadoc for information on the scope of this method.
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Returns a string representation for this entry. Used for formatting error messages.
      Overrides:
      toString in class Object