org.crosswire.common.util

Class ReflectionUtil

java.lang.Object

org.crosswire.common.util.ReflectionUtil

public final class ReflectionUtil
extends Object

Various utilities for calling constructors and methods via introspection.

Author:

Joe Walker, DM Smith

See Also:

The GNU Lesser General Public License for details.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	ReflectionUtil() Prevent instantiation

Method Summary

Methods

Modifier and Type	Method and Description
static <T> T	construct(Class<T> clazz, Object... params) Build an object using the supplied parameters.
static <T> T	construct(String className) Build an object using its default constructor.
static <T> T	construct(String className, Object... params) Build an object using the supplied parameters.
static <T> T	construct(String className, Object[] params, Class<?>[] paramTypes) Build an object using the supplied parameters.
private static Class<?>[]	describeParameters(Object... params) Construct a parallel array of class objects for each element in params.
private static <T> Method	getMethod(Class<T> clazz, String methodName, Class<?>[] calledTypes)
static <T> Object	invoke(Class<T> clazz, Object obj, String methodName, Object... params) Call a method on an object, or statically, with the supplied parameters.
static <T> Object	invoke(Class<T> clazz, Object obj, String methodName, Object[] params, Class<?>[] paramTypes) Call a method on an object, or statically, with the supplied parameters.
static Object	invoke(Object base, String methodName, Object... params) Call a method on a class given a sting
static Object	invoke(String call, Object... params) Call a static method on a class given a string

Methods inherited from class java.lang.Object

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

Constructor Detail

ReflectionUtil

private ReflectionUtil()

Prevent instantiation

Method Detail

construct

public static <T> T construct(String className)
                   throws ClassNotFoundException,
                          InstantiationException,
                          IllegalAccessException

Build an object using its default constructor. Note: a constructor that takes a boolean needs a type of boolean.class, but a parameter of type Boolean. Likewise for other primitives. If this is needed, do not call this method.

Type Parameters:

T - the type of the object to construct

Parameters:

className - the full class name of the object

Returns:

the constructed object

Throws:

ClassNotFoundException - if the class is not found

InstantiationException - if this data represents an abstract class, an interface, an array class, a primitive type, or void; or if the class has no nullary constructor; or if the instantiation fails for some other reason.

IllegalAccessException - if the class or its nullary constructor is not accessible.

construct

public static <T> T construct(String className,
              Object... params)
                   throws ClassNotFoundException,
                          NoSuchMethodException,
                          IllegalAccessException,
                          InvocationTargetException,
                          InstantiationException

Build an object using the supplied parameters. Note: a constructor that takes a boolean needs a type of boolean.class, but a parameter of type Boolean. Likewise for other primitives.

Type Parameters:

T - the type of the object to construct

Parameters:

className - the full class name of the object

params - the constructor's arguments

Returns:

the built object

Throws:

ClassNotFoundException - if the class is not found

NoSuchMethodException - the method does not exist

InstantiationException - if this data represents an abstract class, an interface, an array class, a primitive type, or void; or if the class has no nullary constructor; or if the instantiation fails for some other reason.

IllegalAccessException - if the class or its nullary constructor is not accessible.

InvocationTargetException - if the underlying constructor throws an exception.

InstantiationException - if the class that declares the underlying constructor represents an abstract class.

construct

public static <T> T construct(Class<T> clazz,
              Object... params)
                   throws NoSuchMethodException,
                          InstantiationException,
                          IllegalAccessException,
                          InvocationTargetException

Build an object using the supplied parameters. Note: a constructor that takes a boolean needs a type of boolean.class, but a parameter of type Boolean. Likewise for other primitives.

Type Parameters:

T - the type of the object to construct

Parameters:

clazz - the class of the object

params - the constructor's arguments

Returns:

the built object

Throws:

NoSuchMethodException - the method does not exist

InstantiationException - if the class that declares the underlying constructor represents an abstract class.

IllegalAccessException - if this Constructor object is enforcing Java language access control and the underlying constructor is inaccessible.

InvocationTargetException - if the underlying constructor throws an exception.

construct

public static <T> T construct(String className,
              Object[] params,
              Class<?>[] paramTypes)
                   throws ClassNotFoundException,
                          NoSuchMethodException,
                          IllegalAccessException,
                          InvocationTargetException,
                          InstantiationException

Build an object using the supplied parameters.

Type Parameters:

T - the type of the object to construct

Parameters:

className - the full class name of the object

params - the constructor's arguments

paramTypes - the types of the parameters

Returns:

the built object

Throws:

ClassNotFoundException - if the class is not found

NoSuchMethodException - the method does not exist

InstantiationException - if the class that declares the underlying constructor represents an abstract class.

IllegalAccessException - if this Constructor object is enforcing Java language access control and the underlying constructor is inaccessible.

InvocationTargetException - if the underlying constructor throws an exception.

invoke

public static Object invoke(Object base,
            String methodName,
            Object... params)
                     throws NoSuchMethodException,
                            IllegalAccessException,
                            InvocationTargetException

Call a method on a class given a sting

Parameters:

base - The object to invoke a method on

methodName - The text of the invocation, for example "getName"

params - For example new Object[] { ...}

Returns:

whatever the method returs

Throws:

NoSuchMethodException - the method does not exist

IllegalAccessException - if this Constructor object is enforcing Java language access control and the underlying constructor is inaccessible.

InvocationTargetException - if the underlying constructor throws an exception.

invoke

public static Object invoke(String call,
            Object... params)
                     throws ClassNotFoundException,
                            NoSuchMethodException,
                            IllegalAccessException,
                            InvocationTargetException

Call a static method on a class given a string

Parameters:

call - The text of the invocation, for example "java.lang.String.getName"

params - For example new Object[] { ...}

Returns:

whatever the method returs

Throws:

ClassNotFoundException - if the class is not found

NoSuchMethodException - the method does not exist

IllegalAccessException - if this Constructor object is enforcing Java language access control and the underlying constructor is inaccessible.

InvocationTargetException - if the underlying constructor throws an exception.

invoke

public static <T> Object invoke(Class<T> clazz,
                Object obj,
                String methodName,
                Object... params)
                     throws NoSuchMethodException,
                            IllegalAccessException,
                            InvocationTargetException

Call a method on an object, or statically, with the supplied parameters. Note: a method that takes a boolean needs a type of boolean.class, but a parameter of type Boolean. Likewise for other primitives. If this is needed, do not call this method.

Type Parameters:

T - the type of the object to construct

Parameters:

clazz - the class of the object

obj - the object having the method, or null to call a static method

methodName - the method to be called

params - the parameters

Returns:

whatever the method returns

Throws:

NoSuchMethodException - the method does not exist

IllegalAccessException - if this Constructor object is enforcing Java language access control and the underlying constructor is inaccessible.

InvocationTargetException - if the underlying constructor throws an exception.

invoke

public static <T> Object invoke(Class<T> clazz,
                Object obj,
                String methodName,
                Object[] params,
                Class<?>[] paramTypes)
                     throws NoSuchMethodException,
                            IllegalAccessException,
                            InvocationTargetException

Call a method on an object, or statically, with the supplied parameters. Note: a method that takes a boolean needs a type of boolean.class, but a parameter of type Boolean. Likewise for other primitives.

Type Parameters:

T - the type of the object to construct

Parameters:

clazz - the class of the object

obj - the object having the method, or null to call a static method

methodName - the method to be called

params - the parameters

paramTypes - the types of each of the parameters

Returns:

whatever the method returns

Throws:

NoSuchMethodException - the method does not exist

IllegalAccessException - if this Constructor object is enforcing Java language access control and the underlying constructor is inaccessible.

InvocationTargetException - if the underlying constructor throws an exception.

describeParameters

private static Class<?>[] describeParameters(Object... params)

Construct a parallel array of class objects for each element in params.

Parameters:

params - the types to describe

Returns:

the parallel array of class objects

getMethod

private static <T> Method getMethod(Class<T> clazz,
                   String methodName,
                   Class<?>[] calledTypes)
                         throws NoSuchMethodException

Throws:

NoSuchMethodException