Package org.apache.tapestry5.commons.services

## Interface GenericsResolver

- All Known Implementing Classes:
    `GenericsResolverImpl`, `GuavaGenericsResolver`

      public interface GenericsResolver

  Methods related to the use of Java 5+ generics. Instances should be obtained through `GenericsResolver.Provider.getInstance()`.

  If you have exceptions or bad results with classes using Generics, such as exceptions or missing BeanModel properties, you should try adding the `genericsresolver-guava` Tapestry subproject to our classpath.

  Since:
    5.5.0

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Interface | Description
    --- | --- | ---
    `static class` | `GenericsResolver.Provider` | Convenience class for getting a `GenericsResolver` instance.

  - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `java.lang.Class` | `asClass​(java.lang.reflect.Type actualType)` | Get the class represented by the reflected type.
    `java.lang.reflect.Type` | `extractActualType​(java.lang.reflect.Type containingType, java.lang.reflect.Field field)` | Analyzes the method in the context of containingClass and returns the Class that is represented by the method's generic return type.
    `java.lang.reflect.Type` | `extractActualType​(java.lang.reflect.Type containingType, java.lang.reflect.Method method)` | Analyzes the method in the context of containingClass and returns the Class that is represented by the method's generic return type.
    `java.lang.Class` | `extractGenericFieldType​(java.lang.Class containingClass, java.lang.reflect.Field field)` | Analyzes the field in the context of containingClass and returns the Class that is represented by the field's generic type.
    `java.lang.Class<?>` | `extractGenericReturnType​(java.lang.Class<?> containingClass, java.lang.reflect.Method method)` | Analyzes the method in the context of containingClass and returns the Class that is represented by the method's generic return type.
    `java.lang.reflect.Type` | `resolve​(java.lang.reflect.Type type, java.lang.reflect.Type containingType)` | Resolves the type parameter based on the context of the containingType.

- - ### Method Detail

    - #### extractGenericReturnType

          java.lang.Class<?> extractGenericReturnType​(java.lang.Class<?> containingClass,
                                                      java.lang.reflect.Method method)

      Analyzes the method in the context of containingClass and returns the Class that is represented by the method's generic return type. Any parameter information in the generic return type is lost. If you want to preserve the type parameters of the return type consider using `extractActualType(java.lang.reflect.Type, java.lang.reflect.Method)`.
      Parameters:
        `containingClass` - class which either contains or inherited the method
        `method` - method from which to extract the return type
      Returns:
        the class represented by the methods generic return type, resolved based on the context .
      See Also:
        `resolve(java.lang.reflect.Type,java.lang.reflect.Type)`, `asClass(java.lang.reflect.Type)`

    - #### extractGenericFieldType

          java.lang.Class extractGenericFieldType​(java.lang.Class containingClass,
                                                  java.lang.reflect.Field field)

      Analyzes the field in the context of containingClass and returns the Class that is represented by the field's generic type. Any parameter information in the generic type is lost, if you want to preserve the type parameters of the return type consider using #getTypeVariableIndex(java.lang.reflect.TypeVariable).
      Parameters:
        `containingClass` - class which either contains or inherited the field
        `field` - field from which to extract the type
      Returns:
        the class represented by the field's generic type, resolved based on the containingClass.
      See Also:
        `extractActualType(java.lang.reflect.Type, java.lang.reflect.Field)`, `resolve(java.lang.reflect.Type,java.lang.reflect.Type)`, `asClass(java.lang.reflect.Type)`

    - #### extractActualType

          java.lang.reflect.Type extractActualType​(java.lang.reflect.Type containingType,
                                                   java.lang.reflect.Method method)

      Analyzes the method in the context of containingClass and returns the Class that is represented by the method's generic return type. Any parameter information in the generic return type is lost.
      Parameters:
        `containingType` - Type which is/represents the class that either contains or inherited the method
        `method` - method from which to extract the generic return type
      Returns:
        the generic type represented by the methods generic return type, resolved based on the containingType.
      See Also:
        `resolve(java.lang.reflect.Type,java.lang.reflect.Type)`

    - #### extractActualType

          java.lang.reflect.Type extractActualType​(java.lang.reflect.Type containingType,
                                                   java.lang.reflect.Field field)

      Analyzes the method in the context of containingClass and returns the Class that is represented by the method's generic return type. Any parameter information in the generic return type is lost.
      Parameters:
        `containingType` - Type which is/represents the class that either contains or inherited the field
        `field` - field from which to extract the generic return type
      Returns:
        the generic type represented by the methods generic return type, resolved based on the containingType.
      See Also:
        `resolve(java.lang.reflect.Type,java.lang.reflect.Type)`

    - #### resolve

          java.lang.reflect.Type resolve​(java.lang.reflect.Type type,
                                         java.lang.reflect.Type containingType)

      Resolves the type parameter based on the context of the containingType. `TypeVariable` will be unwrapped to the type argument resolved form the class hierarchy. This may be something other than a simple Class if the type argument is a ParameterizedType for instance (e.g. `List<E>; List<Map<Long, String>>`, E would be returned as a ParameterizedType with the raw type Map and type arguments Long and String.
      Parameters:
        `type` - the generic type (ParameterizedType, GenericArrayType, WildcardType, TypeVariable) to be resolved
        `containingType` - the type which his
      Returns:
        the type resolved to the best of our ability.

    - #### asClass

          java.lang.Class asClass​(java.lang.reflect.Type actualType)

      Get the class represented by the reflected type. This method is lossy; You cannot recover the type information from the class that is returned. `TypeVariable` the first bound is returned. If your type variable extends multiple interfaces that information is lost. `WildcardType` the first lower bound is returned. If the wildcard is defined with upper bounds then `Object` is returned.
      Parameters:
        `actualType` - a Class, ParameterizedType, GenericArrayType
      Returns:
        the un-parameterized class associated with the type.