org.apache.flink.api.java.typeutils

Class TypeExtractionUtils

java.lang.Object

org.apache.flink.api.java.typeutils.TypeExtractionUtils

@Internal
public class TypeExtractionUtils
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	TypeExtractionUtils.LambdaExecutable Similar to a Java 8 Executable but with a return type.

Method Summary

Modifier and Type	Method and Description
static TypeExtractionUtils.LambdaExecutable	checkAndExtractLambda(Function function) Checks if the given function has been implemented using a Java 8 lambda.
static Type	extractTypeArgument(Type t, int index) This method extracts the n-th type argument from the given type.
static Type	extractTypeFromLambda(Class<?> baseClass, TypeExtractionUtils.LambdaExecutable exec, int[] lambdaTypeArgumentIndices, int paramLen, int baseParametersLen) Extracts type from given index from lambda.
static List<Method>	getAllDeclaredMethods(Class<?> clazz) Returns all declared methods of a class including methods of superclasses.
static Class<?>	getRawClass(Type t) Returns the raw class of both parameterized types and generic arrays.
static Method	getSingleAbstractMethod(Class<?> baseClass) Extracts a Single Abstract Method (SAM) as defined in Java Specification (4.3.2.
static Type	getTypeHierarchy(List<Type> typeHierarchy, Type t, Class<?> stopAtClass) Traverses the type hierarchy of a type up until a certain stop class is found.
static boolean	hasSuperclass(Class<?> clazz, String superClassName) Returns true if the given class has a superclass of given name.
static boolean	isClassType(Type t) Checks if a type can be converted to a Class.
static boolean	sameTypeVars(Type t1, Type t2) Checks whether two types are type variables describing the same.
static <T> Class<T>	typeToClass(Type t) Convert ParameterizedType or Class to a Class.
static void	validateLambdaType(Class<?> baseClass, Type t) Checks whether the given type has the generic parameters declared in the class definition.

Methods inherited from class java.lang.Object

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

Method Detail

checkAndExtractLambda

public static TypeExtractionUtils.LambdaExecutable checkAndExtractLambda(Function function)
                                                                  throws TypeExtractionException

Checks if the given function has been implemented using a Java 8 lambda. If yes, a LambdaExecutable is returned describing the method/constructor. Otherwise null.

Throws:

TypeExtractionException - lambda extraction is pretty hacky, it might fail for unknown JVM issues.

extractTypeFromLambda

public static Type extractTypeFromLambda(Class<?> baseClass,
                                         TypeExtractionUtils.LambdaExecutable exec,
                                         int[] lambdaTypeArgumentIndices,
                                         int paramLen,
                                         int baseParametersLen)

Extracts type from given index from lambda. It supports nested types.

Parameters:

baseClass - SAM function that the lambda implements

exec - lambda function to extract the type from

lambdaTypeArgumentIndices - position of type to extract in type hierarchy

paramLen - count of total parameters of the lambda (including closure parameters)

baseParametersLen - count of lambda interface parameters (without closure parameters)

Returns:

extracted type

extractTypeArgument

public static Type extractTypeArgument(Type t,
                                       int index)
                                throws InvalidTypesException

This method extracts the n-th type argument from the given type. An InvalidTypesException is thrown if the type does not have any type arguments or if the index exceeds the number of type arguments.

Parameters:

t - Type to extract the type arguments from

index - Index of the type argument to extract

Returns:

The extracted type argument

Throws:

InvalidTypesException - if the given type does not have any type arguments or if the index exceeds the number of type arguments.

getSingleAbstractMethod

public static Method getSingleAbstractMethod(Class<?> baseClass)

Extracts a Single Abstract Method (SAM) as defined in Java Specification (4.3.2. The Class Object, 9.8 Functional Interfaces, 9.4.3 Interface Method Body) from given class.

Parameters:

baseClass - a class that is a FunctionalInterface to retrieve a SAM from

Returns:

single abstract method of the given class

Throws:

InvalidTypesException - if the given class does not implement FunctionalInterface

getAllDeclaredMethods

public static List<Method> getAllDeclaredMethods(Class<?> clazz)

Returns all declared methods of a class including methods of superclasses.

typeToClass

public static <T> Class<T> typeToClass(Type t)

Convert ParameterizedType or Class to a Class.

isClassType

public static boolean isClassType(Type t)

Checks if a type can be converted to a Class. This is true for ParameterizedType and Class.

sameTypeVars

public static boolean sameTypeVars(Type t1,
                                   Type t2)

Checks whether two types are type variables describing the same.

getTypeHierarchy

public static Type getTypeHierarchy(List<Type> typeHierarchy,
                                    Type t,
                                    Class<?> stopAtClass)

Traverses the type hierarchy of a type up until a certain stop class is found.

Parameters:

t - type for which a hierarchy need to be created

Returns:

type of the immediate child of the stop class

hasSuperclass

public static boolean hasSuperclass(Class<?> clazz,
                                    String superClassName)

Returns true if the given class has a superclass of given name.

Parameters:

clazz - class to be analyzed

superClassName - class name of the super class

getRawClass

public static Class<?> getRawClass(Type t)

Returns the raw class of both parameterized types and generic arrays. Returns java.lang.Object for all other types.

validateLambdaType

public static void validateLambdaType(Class<?> baseClass,
                                      Type t)

Checks whether the given type has the generic parameters declared in the class definition.

Parameters:

t - type to be validated