Module org.joda.convert
Package org.joda.convert

Class StringConvert

java.lang.Object
org.joda.convert.StringConvert
public final class StringConvert extends Object
Manager for conversion to and from a String, acting as the main client interface.

Support is provided for conversions based on the StringConverter interface or the ToString and FromString annotations.

StringConvert is thread-safe with concurrent caches.

  • Field Details

  • Constructor Details

    • StringConvert

      public StringConvert()
      Creates a new conversion manager including the JDK converters.

      The convert instance is mutable in a thread-safe manner. Converters may be altered at any time, including the JDK converters. It is strongly recommended to only alter the converters before performing actual conversions.

    • StringConvert

      public StringConvert(boolean includeJdkConverters, StringConverterFactory... factories)
      Creates a new conversion manager.

      The convert instance is mutable in a thread-safe manner. Converters may be altered at any time, including the JDK converters. It is strongly recommended to only alter the converters before performing actual conversions.

      If specified, the factories will be queried in the order specified.

      Parameters:
      includeJdkConverters - true to include the JDK converters
      factories - optional array of factories to use, not null

  • Method Details

    • create

      public static StringConvert create()
      Creates a new conversion manager including the extended standard set of converters.

      The returned converter is a new instance that includes additional converters:

      The convert instance is mutable in a thread-safe manner. Converters may be altered at any time, including the JDK converters. It is strongly recommended to only alter the converters before performing actual conversions.

      Returns:
      the new converter, not null
      Since:
      1.5

    • convertToString

      public String convertToString(Object object)
      Converts the specified object to a String.

      This uses findConverter(java.lang.Class<T>) to provide the converter.

      Parameters:
      object - the object to convert, null returns null
      Returns:
      the converted string, may be null
      Throws:
      RuntimeException - (or subclass) if unable to convert

    • convertToString

      public String convertToString(Class<?> cls, Object object)
      Converts the specified object to a String.

      This uses findConverter(java.lang.Class<T>) to provide the converter. The class can be provided to select a more specific converter.

      Parameters:
      cls - the class to convert from, not null
      object - the object to convert, null returns null
      Returns:
      the converted string, may be null
      Throws:
      RuntimeException - (or subclass) if unable to convert

    • convertFromString

      public <T> T convertFromString(Class<T> cls, String str)
      Converts the specified object from a String.

      This uses findFromStringConverter(java.lang.Class<T>) to provide the converter.

      Type Parameters:
      T - the type to convert to
      Parameters:
      cls - the class to convert to, not null
      str - the string to convert, null returns null
      Returns:
      the converted object, may be null
      Throws:
      RuntimeException - (or subclass) if unable to convert

    • isConvertible

      public boolean isConvertible(Class<?> cls)
      Checks if a suitable converter exists for the type.

      This performs the same checks as the findConverter methods. Calling this before findConverter will cache the converter.

      Note that all exceptions, including developer errors are caught and hidden.

      Parameters:
      cls - the class to find a converter for, null returns false
      Returns:
      true if convertible
      Since:
      1.5

    • converterFor

      public <T> Optional<TypedStringConverter<T>> converterFor(Class<T> cls)
      Finds a suitable converter for the type.

      This returns an instance of TypedStringConverter for the specified class. This is designed for user code where the Class object generics is known.

      The search algorithm first searches the registered converters. It then searches for ToString and FromString annotations on the specified class, class hierarchy or immediate parent interfaces. Finally, it handles Enum instances.

      The returned converter may be queried for the effective type of the conversion. This can be used to find the best type to send in a serialized form.

      Unusually for a method returning Optional, the method can also throw an exception. An empty result indicates that there is no converter for the specified class. An exception indicates there is a developer error in one of the converter factories.

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to find a converter for, not null
      Returns:
      the converter, empty if not found
      Throws:
      IllegalArgumentException - if the input class is null
      RuntimeException - (or subclass) if there is a developer error in one of the converter factories
      Since:
      3.0

    • fromStringConverterFor

      public <T> Optional<org.joda.convert.TypedFromStringConverter<T>> fromStringConverterFor(Class<T> cls)
      Finds a suitable from-string converter for the type.

      This returns an instance of FromStringConverter for the specified class. In most cases this is identical to findConverter(Class). However, it is permitted to have a FromString annotation without a ToString annotation, and this method handles that use case.

      Unusually for a method returning Optional, the method can also throw an exception. An empty result indicates that there is no converter for the specified class. An exception indicates there is a developer error in one of the converter factories.

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to find a converter for, not null
      Returns:
      the converter, not null
      Throws:
      IllegalArgumentException - if the input class is null
      RuntimeException - (or subclass) if there is a developer error in one of the converters
      Since:
      3.0

    • findConverter

      public <T> StringConverter<T> findConverter(Class<T> cls)
      Finds a suitable converter for the type.

      This returns an instance of StringConverter for the specified class. This is designed for user code where the Class object generics is known.

      The search algorithm first searches the registered converters. It then searches for ToString and FromString annotations on the specified class, class hierarchy or immediate parent interfaces. Finally, it handles Enum instances.

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to find a converter for, not null
      Returns:
      the converter, not null
      Throws:
      RuntimeException - (or subclass) if no converter found

    • findConverterNoGenerics

      public StringConverter<Object> findConverterNoGenerics(Class<?> cls)
      Finds a suitable converter for the type with open generics.

      This returns an instance of StringConverter for the specified class. This is designed for framework usage where the Class object generics are unknown'?'. The returned type is declared with Object instead of '?' to allow the ToStringConverter to be invoked.

      The search algorithm first searches the registered converters. It then searches for ToString and FromString annotations on the specified class, class hierarchy or immediate parent interfaces. Finally, it handles Enum instances.

      Parameters:
      cls - the class to find a converter for, not null
      Returns:
      the converter, using Object to avoid generics, not null
      Throws:
      RuntimeException - (or subclass) if no converter found
      Since:
      1.5

    • findTypedConverter

      public <T> TypedStringConverter<T> findTypedConverter(Class<T> cls)
      Finds a suitable converter for the type.

      This returns an instance of TypedStringConverter for the specified class. This is designed for user code where the Class object generics is known.

      The search algorithm first searches the registered converters. It then searches for ToString and FromString annotations on the specified class, class hierarchy or immediate parent interfaces. Finally, it handles Enum instances.

      The returned converter may be queried for the effective type of the conversion. This can be used to find the best type to send in a serialized form.

      NOTE: Changing the method return type of findConverter(Class) would be source compatible but not binary compatible. As this is a low-level library, binary compatibility is important, hence the addition of this method.

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to find a converter for, not null
      Returns:
      the converter, not null
      Throws:
      RuntimeException - (or subclass) if no converter found
      Since:
      1.7

    • findTypedConverterNoGenerics

      public TypedStringConverter<Object> findTypedConverterNoGenerics(Class<?> cls)
      Finds a suitable converter for the type with open generics.

      This returns an instance of TypedStringConverter for the specified class. This is designed for framework usage where the Class object generics are unknown'?'. The returned type is declared with Object instead of '?' to allow the ToStringConverter to be invoked.

      The search algorithm first searches the registered converters. It then searches for ToString and FromString annotations on the specified class, class hierarchy or immediate parent interfaces. Finally, it handles Enum instances.

      The returned converter may be queried for the effective type of the conversion. This can be used to find the best type to send in a serialized form.

      NOTE: Changing the method return type of findConverterNoGenerics(Class) would be source compatible but not binary compatible. As this is a low-level library, binary compatibility is important, hence the addition of this method.

      Parameters:
      cls - the class to find a converter for, not null
      Returns:
      the converter, using Object to avoid generics, not null
      Throws:
      RuntimeException - (or subclass) if no converter found
      Since:
      1.7

    • findFromStringConverter

      public <T> FromStringConverter<T> findFromStringConverter(Class<T> cls)
      Finds a suitable from-string converter for the type.

      This returns an instance of FromStringConverter for the specified class. In most cases this is identical to findConverter(Class). However, it is permitted to have a FromString annotation without a ToString annotation, and this method handles that use case.

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to find a converter for, not null
      Returns:
      the converter, not null
      Throws:
      RuntimeException - (or subclass) if no converter found

    • registerFactory

      public void registerFactory(StringConverterFactory factory)
      Registers a converter factory.

      This will be registered ahead of all existing factories.

      No new factories may be registered for the global singleton.

      Parameters:
      factory - the converter factory, not null
      Throws:
      IllegalStateException - if trying to alter the global singleton
      Since:
      1.5

    • register

      public <T> void register(Class<T> cls, StringConverter<T> converter)
      Registers a converter for a specific type.

      The converter will be used for subclasses unless overidden.

      No new converters may be registered for the global singleton.

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to register a converter for, not null
      converter - the String converter, not null
      Throws:
      IllegalArgumentException - if the class or converter are null
      IllegalStateException - if trying to alter the global singleton

    • register

      public <T> void register(Class<T> cls, ToStringConverter<T> toString, FromStringConverter<T> fromString)
      Registers a converter for a specific type using two separate converters.

      This method registers a converter for the specified class. It is primarily intended for use with JDK 1.8 method references or lambdas: 

        sc.register(Distance.class, Distance::toString, Distance::parse);
      The converter will be used for subclasses unless overidden.

      No new converters may be registered for the global singleton.

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to register a converter for, not null
      toString - the to String converter, typically a method reference, not null
      fromString - the from String converter, typically a method reference, not null
      Throws:
      IllegalArgumentException - if the class or converter are null
      IllegalStateException - if trying to alter the global singleton
      Since:
      1.3

    • registerMethods

      public <T> void registerMethods(Class<T> cls, String toStringMethodName, String fromStringMethodName)
      Registers a converter for a specific type by method names.

      This method allows the converter to be used when the target class cannot have annotations added. The two method names must obey the same rules as defined by the annotations ToString and FromString. The converter will be used for subclasses unless overidden.

      No new converters may be registered for the global singleton.

      For example, convert.registerMethods(Distance.class, "toString", "parse");

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to register a converter for, not null
      toStringMethodName - the name of the method converting to a string, not null
      fromStringMethodName - the name of the method converting from a string, not null
      Throws:
      IllegalArgumentException - if the class or method name are null or invalid
      IllegalStateException - if trying to alter the global singleton

    • registerMethodConstructor

      public <T> void registerMethodConstructor(Class<T> cls, String toStringMethodName)
      Registers a converter for a specific type by method and constructor.

      This method allows the converter to be used when the target class cannot have annotations added. The two method name and constructor must obey the same rules as defined by the annotations ToString and FromString. The converter will be used for subclasses unless overidden.

      No new converters may be registered for the global singleton.

      For example, convert.registerMethodConstructor(Distance.class, "toString");

      Type Parameters:
      T - the type of the converter
      Parameters:
      cls - the class to register a converter for, not null
      toStringMethodName - the name of the method converting to a string, not null
      Throws:
      IllegalArgumentException - if the class or method name are null or invalid
      IllegalStateException - if trying to alter the global singleton

    • toString

      public String toString()
      Returns a simple string representation of the object.
      Overrides:
      toString in class Object
      Returns:
      the string representation, never null