org.apache.giraph.utils

Class ReflectionUtils

java.lang.Object

org.apache.giraph.utils.ReflectionUtils

public class ReflectionUtils
extends Object

Helper methods to get type arguments to generic classes. Courtesy of Ian Robertson (overstock.com). Make sure to use with abstract generic classes, not interfaces.

Method Summary

Modifier and Type	Method and Description
static String	getPackagePath(Class klass) Get package path to the class given.
static String	getPackagePath(Object object) Get package path to the object given.
static <T> Class<?>[]	getTypeArguments(Class<T> baseClass, Class<? extends T> childClass) Get the actual type arguments a child class has used to extend a generic base class.
static <T> T	newInstance(Class<T> theClass) Instantiate a class, wrap exceptions
static <T> T	newInstance(Class<T> theClass, ImmutableClassesGiraphConfiguration configuration) Instantiate classes that are ImmutableClassesGiraphConfigurable
static <T> T	newInstance(Class<T> theClass, ImmutableClassesGiraphConfiguration configuration, org.apache.hadoop.mapreduce.Mapper.Context context) Instantiate classes that are ImmutableClassesGiraphConfigurable, and optionally set context on them if they are ContextSettable
static void	verifyConcrete(Class<?> concrete, String typeDesc) Verify that given type is a concrete type that can be instantiated.
static void	verifyTypes(Class<?> concreteChild, Class<?> parent, String typeDesc, Class<?> mainClass) Verify that found type matches the expected type.

Methods inherited from class java.lang.Object

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

Method Detail

getPackagePath

public static String getPackagePath(Object object)

Get package path to the object given. Used with resources.

Parameters:

object - the Object to check

Returns:

Path to package of object

getPackagePath

public static String getPackagePath(Class klass)

Get package path to the class given. Used with resources.

Parameters:

klass - Class to check

Returns:

Path to package of class

getTypeArguments

public static <T> Class<?>[] getTypeArguments(Class<T> baseClass,
                                              Class<? extends T> childClass)

Get the actual type arguments a child class has used to extend a generic base class.

Type Parameters:

T - Type to evaluate.

Parameters:

baseClass - the base class

childClass - the child class

Returns:

a list of the raw classes for the actual type arguments.

newInstance

public static <T> T newInstance(Class<T> theClass)

Instantiate a class, wrap exceptions

Type Parameters:

T - Type to instantiate

Parameters:

theClass - Class to instantiate

Returns:

Newly instantiated object

newInstance

public static <T> T newInstance(Class<T> theClass,
                                ImmutableClassesGiraphConfiguration configuration)

Instantiate classes that are ImmutableClassesGiraphConfigurable

Type Parameters:

T - Type to instantiate

Parameters:

theClass - Class to instantiate

configuration - Giraph configuration, may be null

Returns:

Newly instantiated object with configuration set if possible

newInstance

public static <T> T newInstance(Class<T> theClass,
                                ImmutableClassesGiraphConfiguration configuration,
                                org.apache.hadoop.mapreduce.Mapper.Context context)

Instantiate classes that are ImmutableClassesGiraphConfigurable, and optionally set context on them if they are ContextSettable

Type Parameters:

T - Type to instantiate

Parameters:

theClass - Class to instantiate

configuration - Giraph configuration, may be null

context - Mapper context

Returns:

Newly instantiated object with configuration and context set if possible

verifyTypes

public static void verifyTypes(Class<?> concreteChild,
                               Class<?> parent,
                               String typeDesc,
                               Class<?> mainClass)

Verify that found type matches the expected type. If types don't match an IllegalStateException will be thrown.

Parameters:

concreteChild - Concrete child type

parent - Parent type

typeDesc - String description of the type (for exception description)

mainClass - Class in which the actual type was found (for exception description)

verifyConcrete

public static void verifyConcrete(Class<?> concrete,
                                  String typeDesc)

Verify that given type is a concrete type that can be instantiated.

Parameters:

concrete - type to check

typeDesc - String description of the type (for exception description)