Package org.apache.commons.collections

Class TransformerUtils

java.lang.Object
org.apache.commons.collections.TransformerUtils
@Deprecated(since="2021-04-30") public class TransformerUtils extends Object
Deprecated.
Apache Commons Collections version 3.x is being deprecated from AEMaaCS. The upgraded version 4.4 of Commons Collections is already included as replacement. Customers are advised to upgrade to this version of the library. Please note: the package name was changed to org.apache.commons.collections4. Further note that there are AEM APIs currently exposing the old collections classes; these will be updated in upcoming releases.
TransformerUtils provides reference implementations and utilities for the Transformer functor interface. The supplied transformers are:
  • Invoker - returns the result of a method call on the input object
  • Clone - returns a clone of the input object
  • Constant - always returns the same object
  • Closure - performs a Closure and returns the input object
  • Predicate - returns the result of the predicate as a Boolean
  • Factory - returns a new object from a factory
  • Chained - chains two or more transformers together
  • Switch - calls one transformer based on one or more predicates
  • SwitchMap - calls one transformer looked up from a Map
  • Instantiate - the Class input object is instantiated
  • Map - returns an object from a supplied Map
  • Null - always returns null
  • NOP - returns the input object, which should be immutable
  • Exception - always throws an exception
  • StringValue - returns a java.lang.String representation of the input object
All the supplied transformers are Serializable.
Since:
Commons Collections 3.0

  • Constructor Details

    • TransformerUtils

      public TransformerUtils()
      Deprecated.
      This class is not normally instantiated.

  • Method Details

    • exceptionTransformer

      public static Transformer exceptionTransformer()
      Deprecated.
      Gets a transformer that always throws an exception. This could be useful during testing as a placeholder.
      Returns:
      the transformer
      See Also:

    • nullTransformer

      public static Transformer nullTransformer()
      Deprecated.
      Gets a transformer that always returns null.
      Returns:
      the transformer
      See Also:

    • nopTransformer

      public static Transformer nopTransformer()
      Deprecated.
      Gets a transformer that returns the input object. The input object should be immutable to maintain the contract of Transformer (although this is not checked).
      Returns:
      the transformer
      See Also:

    • cloneTransformer

      public static Transformer cloneTransformer()
      Deprecated.
      Gets a transformer that returns a clone of the input object. The input object will be cloned using one of these techniques (in order):
      • public clone method
      • public copy constructor
      • serialization clone
        Returns:
        the transformer
        See Also:

      • constantTransformer

        public static Transformer constantTransformer(Object constantToReturn)
        Deprecated.
        Creates a Transformer that will return the same object each time the transformer is used.
        Parameters:
        constantToReturn - the constant object to return each time in the transformer
        Returns:
        the transformer.
        See Also:

      • asTransformer

        public static Transformer asTransformer(Closure closure)
        Deprecated.
        Creates a Transformer that calls a Closure each time the transformer is used. The transformer returns the input object.
        Parameters:
        closure - the closure to run each time in the transformer, not null
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the closure is null
        See Also:

      • asTransformer

        public static Transformer asTransformer(Predicate predicate)
        Deprecated.
        Creates a Transformer that calls a Predicate each time the transformer is used. The transformer will return either Boolean.TRUE or Boolean.FALSE.
        Parameters:
        predicate - the predicate to run each time in the transformer, not null
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the predicate is null
        See Also:

      • asTransformer

        public static Transformer asTransformer(Factory factory)
        Deprecated.
        Creates a Transformer that calls a Factory each time the transformer is used. The transformer will return the value returned by the factory.
        Parameters:
        factory - the factory to run each time in the transformer, not null
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the factory is null
        See Also:

      • chainedTransformer

        public static Transformer chainedTransformer(Transformer transformer1, Transformer transformer2)
        Deprecated.
        Create a new Transformer that calls two transformers, passing the result of the first into the second.
        Parameters:
        transformer1 - the first transformer
        transformer2 - the second transformer
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if either transformer is null
        See Also:

      • chainedTransformer

        public static Transformer chainedTransformer(Transformer[] transformers)
        Deprecated.
        Create a new Transformer that calls each transformer in turn, passing the result into the next transformer.
        Parameters:
        transformers - an array of transformers to chain
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the transformers array is null
        IllegalArgumentException - if any transformer in the array is null
        See Also:

      • chainedTransformer

        public static Transformer chainedTransformer(Collection transformers)
        Deprecated.
        Create a new Transformer that calls each transformer in turn, passing the result into the next transformer. The ordering is that of the iterator() method on the collection.
        Parameters:
        transformers - a collection of transformers to chain
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the transformers collection is null
        IllegalArgumentException - if any transformer in the collection is null
        See Also:

      • switchTransformer

        public static Transformer switchTransformer(Predicate predicate, Transformer trueTransformer, Transformer falseTransformer)
        Deprecated.
        Create a new Transformer that calls one of two transformers depending on the specified predicate.
        Parameters:
        predicate - the predicate to switch on
        trueTransformer - the transformer called if the predicate is true
        falseTransformer - the transformer called if the predicate is false
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the predicate is null
        IllegalArgumentException - if either transformer is null
        See Also:

      • switchTransformer

        public static Transformer switchTransformer(Predicate[] predicates, Transformer[] transformers)
        Deprecated.
        Create a new Transformer that calls one of the transformers depending on the predicates. The transformer at array location 0 is called if the predicate at array location 0 returned true. Each predicate is evaluated until one returns true. If no predicates evaluate to true, null is returned.
        Parameters:
        predicates - an array of predicates to check
        transformers - an array of transformers to call
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the either array is null
        IllegalArgumentException - if the either array has 0 elements
        IllegalArgumentException - if any element in the arrays is null
        IllegalArgumentException - if the arrays are different sizes
        See Also:

      • switchTransformer

        public static Transformer switchTransformer(Predicate[] predicates, Transformer[] transformers, Transformer defaultTransformer)
        Deprecated.
        Create a new Transformer that calls one of the transformers depending on the predicates. The transformer at array location 0 is called if the predicate at array location 0 returned true. Each predicate is evaluated until one returns true. If no predicates evaluate to true, the default transformer is called. If the default transformer is null, null is returned.
        Parameters:
        predicates - an array of predicates to check
        transformers - an array of transformers to call
        defaultTransformer - the default to call if no predicate matches, null means return null
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the either array is null
        IllegalArgumentException - if the either array has 0 elements
        IllegalArgumentException - if any element in the arrays is null
        IllegalArgumentException - if the arrays are different sizes
        See Also:

      • switchTransformer

        public static Transformer switchTransformer(Map predicatesAndTransformers)
        Deprecated.
        Create a new Transformer that calls one of the transformers depending on the predicates.

        The Map consists of Predicate keys and Transformer values. A transformer is called if its matching predicate returns true. Each predicate is evaluated until one returns true. If no predicates evaluate to true, the default transformer is called. The default transformer is set in the map with a null key. If no default transformer is set, null will be returned in a default case. The ordering is that of the iterator() method on the entryset collection of the map.

        Parameters:
        predicatesAndTransformers - a map of predicates to transformers
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the map is null
        IllegalArgumentException - if the map is empty
        IllegalArgumentException - if any transformer in the map is null
        ClassCastException - if the map elements are of the wrong type
        See Also:

      • switchMapTransformer

        public static Transformer switchMapTransformer(Map objectsAndTransformers)
        Deprecated.
        Create a new Transformer that uses the input object as a key to find the transformer to call.

        The Map consists of object keys and Transformer values. A transformer is called if the input object equals the key. If there is no match, the default transformer is called. The default transformer is set in the map using a null key. If no default is set, null will be returned in a default case.

        Parameters:
        objectsAndTransformers - a map of objects to transformers
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the map is null
        IllegalArgumentException - if the map is empty
        IllegalArgumentException - if any transformer in the map is null
        See Also:

      • instantiateTransformer

        public static Transformer instantiateTransformer()
        Deprecated.
        Gets a Transformer that expects an input Class object that it will instantiate.
        Returns:
        the transformer
        See Also:

      • instantiateTransformer

        public static Transformer instantiateTransformer(Class[] paramTypes, Object[] args)
        Deprecated.
        Creates a Transformer that expects an input Class object that it will instantiate. The constructor used is determined by the arguments specified to this method.
        Parameters:
        paramTypes - parameter types for the constructor, can be null
        args - the arguments to pass to the constructor, can be null
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the paramTypes and args don't match
        See Also:

      • mapTransformer

        public static Transformer mapTransformer(Map map)
        Deprecated.
        Creates a Transformer that uses the passed in Map to transform the input object (as a simple lookup).
        Parameters:
        map - the map to use to transform the objects
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the map is null
        See Also:

      • invokerTransformer

        public static Transformer invokerTransformer(String methodName)
        Deprecated.
        Gets a Transformer that invokes a method on the input object. The method must have no parameters. If the input object is null, null is returned.

        For example, TransformerUtils.invokerTransformer("getName"); will call the getName/code> method on the input object to determine the transformer result.

        Parameters:
        methodName - the method name to call on the input object, may not be null
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the methodName is null.
        See Also:

      • invokerTransformer

        public static Transformer invokerTransformer(String methodName, Class[] paramTypes, Object[] args)
        Deprecated.
        Gets a Transformer that invokes a method on the input object. The method parameters are specified. If the input object is null, null is returned.
        Parameters:
        methodName - the name of the method
        paramTypes - the parameter types
        args - the arguments
        Returns:
        the transformer
        Throws:
        IllegalArgumentException - if the method name is null
        IllegalArgumentException - if the paramTypes and args don't match
        See Also:

      • stringValueTransformer

        public static Transformer stringValueTransformer()
        Deprecated.
        Gets a transformer that returns a java.lang.String representation of the input object. This is achieved via the toString method, null returns 'null'.
        Returns:
        the transformer
        See Also: