Package org.dellroad.stuff.java

Class ReflectUtil

java.lang.Object

org.dellroad.stuff.java.ReflectUtil

public final class ReflectUtil
extends Object

Reflection utility methods.

Method Summary

Modifier and Type	Method	Description
static Map<String,List<Method>>	findPropertySetters(Class<?> type, String methodPrefix)	Find all setter methods in the given class whose name starts with the given prefix.
static Comparator<Class<?>>	getClassComparator()	Get a comparator that partially orders types where narrower types sort first.
static Comparator<Class<?>>	getClassComparator(boolean incomparableEqual)	Get a comparator that calculates which type is narrower, if possible.
static <T> T	instantiate(Class<T> type)	Instantiate the given class using its zero-arg constructor.
static <T> T	instantiate(Constructor<T> constructor, Object... params)	Instantiate the given class using the given constructor.
static Object	invoke(Method method, Object target, Object... params)	Invoke the given method, rethrowing any checked exceptions.
static String	propertyNameFromGetterMethod(Method method)	Get the Java bean name corresponding to the given Java bean property getter method.
static String	propertyNameFromGetterMethodName(String methodName)	Get the Java bean name corresponding to the given Java bean property getter method name.
static void	sortByType(List<? extends Class<?>> list)	Sort the given list so narrower types always appear before wider types.
static <T> void	sortByType(List<T> list, Function<? super T,? extends Class<?>> typer)	Sort the given list so items with narrower types always appear before items with wider types.

Methods inherited from class java.lang.Object

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

Method Details

propertyNameFromGetterMethod

public static String propertyNameFromGetterMethod(Method method)

Get the Java bean name corresponding to the given Java bean property getter method.

The method does not need to be public.

Does not support indexed bean properties.

Parameters:

method - getter method

Returns:

corresponding bean property name, or null if method is not a valid Java bean getter method

Throws:

IllegalArgumentException - if method is null

propertyNameFromGetterMethodName

public static String propertyNameFromGetterMethodName(String methodName)

Get the Java bean name corresponding to the given Java bean property getter method name.

This method assumes that if the name starts with "is", then the caller has already verified any corresponding method has return type boolean.

Parameters:

methodName - getter method name

Returns:

corresponding bean property name, or null if methodName is not a value property getter method name

Throws:

IllegalArgumentException - if methodName is null

findPropertySetters

public static Map<String,List<Method>> findPropertySetters(Class<?> type,
 String methodPrefix)

Find all setter methods in the given class whose name starts with the given prefix.

A setter method is any public method taking exactly one parameter. Multiple setter methods could have the same name, if they have a different parameter type and/or return type, though method will filter out bridge methods.

Parameters:

type - type to introspect

methodPrefix - setter method name prefix (typically "set")

Returns:

mapping from property name to setter methods, with those having narrower parameter types first

Throws:

IllegalArgumentException - if either parameter is null

instantiate

public static <T> T instantiate(Class<T> type)

Instantiate the given class using its zero-arg constructor.

Type Parameters:

T - new object type

Parameters:

type - type to instantiate

Returns:

new instance

Throws:

RuntimeException - if construction fails

IllegalArgumentException - if type is null

instantiate

public static <T> T instantiate(Constructor<T> constructor,
 Object... params)

Instantiate the given class using the given constructor.

Type Parameters:

T - new object type

Parameters:

constructor - constructor to invoke

params - constructor parameters

Returns:

method's return value

Throws:

RuntimeException - if construction fails

IllegalArgumentException - if either parameter is null

invoke

public static Object invoke(Method method,
 Object target,
 Object... params)

Invoke the given method, rethrowing any checked exceptions.

Parameters:

method - method to invoke

target - target object, or null if method is static

params - constructor parameters

Returns:

method's return value

Throws:

RuntimeException - if invocation fails

IllegalArgumentException - if method or params is null

sortByType

public static void sortByType(List<? extends Class<?>> list)

Sort the given list so narrower types always appear before wider types.

This is a stable sort. Algorithm is O(n2) however.

Parameters:

list - list of types

sortByType

public static <T> void sortByType(List<T> list,
 Function<? super T,? extends Class<?>> typer)

Sort the given list so items with narrower types always appear before items with wider types.

This is a stable sort. Algorithm is O(n2) however.

Parameters:

list - list of items

typer - associates a type with each item

getClassComparator

public static Comparator<Class<?>> getClassComparator()

Get a comparator that partially orders types where narrower types sort first.

Non-comparable types compare as equal, so they will not reorder under a stable sort.

Returns:

stable ordering of types narrowest first

getClassComparator

public static Comparator<Class<?>> getClassComparator(boolean incomparableEqual)

Get a comparator that calculates which type is narrower, if possible.

Non-comparable types will compare as equal if incomparableEqual is true, or else generate an IllegalArgumentException.

Warning: use this comparator for simple comparisons only; it will not work for sorting because it is not transitive for "equality"; use sortByType() instead.

Parameters:

incomparableEqual - true to return zero for incomparable classes, false to throw IllegalArgumentException

Returns:

ordering of types narrowest first