org.apache.commons.lang.reflect
Class MethodUtils

java.lang.Object
  org.apache.commons.lang.reflect.MethodUtils

public class MethodUtils
extends Object

Utility reflection methods focused on methods, originally from Commons BeanUtils. Differences from the BeanUtils version may be noted, especially where similar functionality already existed within Lang.

Known Limitations

Accessing Public Methods In A Default Access Superclass

There is an issue when invoking public methods contained in a default access superclass on JREs prior to 1.4. Reflection locates these methods fine and correctly assigns them as public. However, an IllegalAccessException is thrown if the method is invoked.

MethodUtils contains a workaround for this situation. It will attempt to call setAccessible on this method. If this call succeeds, then the method can be invoked as normal. This call will only succeed when the application has sufficient security privileges. If this call fails then the method may fail.

Since:

2.5

Version:

$Id: MethodUtils.java 911986 2010-02-19 21:19:05Z niallp $

Author:

Apache Software Foundation, Craig R. McClanahan, Ralph Schaer, Chris Audley, Rey François, Gregor Raýman, Jan Sorensen, Robert Burrell Donkin, Matt Benson

Constructor Summary

MethodUtils()
MethodUtils instances should NOT be constructed in standard programming.

Method Summary

static Method	getAccessibleMethod(Class cls, String methodName, Class parameterType) Return an accessible method (that is, one that can be invoked via reflection) with given name and a single parameter.
static Method	getAccessibleMethod(Class cls, String methodName, Class[] parameterTypes) Return an accessible method (that is, one that can be invoked via reflection) with given name and parameters.
static Method	getAccessibleMethod(Method method) Return an accessible method (that is, one that can be invoked via reflection) that implements the specified Method.
static Method	getMatchingAccessibleMethod(Class cls, String methodName, Class[] parameterTypes) Find an accessible method that matches the given name and has compatible parameters.
static Object	invokeExactMethod(Object object, String methodName, Object arg) Invoke a method whose parameter type matches exactly the object type.
static Object	invokeExactMethod(Object object, String methodName, Object[] args) Invoke a method whose parameter types match exactly the object types.
static Object	invokeExactMethod(Object object, String methodName, Object[] args, Class[] parameterTypes) Invoke a method whose parameter types match exactly the parameter types given.
static Object	invokeExactStaticMethod(Class cls, String methodName, Object arg) Invoke a static method whose parameter type matches exactly the object type.
static Object	invokeExactStaticMethod(Class cls, String methodName, Object[] args) Invoke a static method whose parameter types match exactly the object types.
static Object	invokeExactStaticMethod(Class cls, String methodName, Object[] args, Class[] parameterTypes) Invoke a static method whose parameter types match exactly the parameter types given.
static Object	invokeMethod(Object object, String methodName, Object arg) Invoke a named method whose parameter type matches the object type.
static Object	invokeMethod(Object object, String methodName, Object[] args) Invoke a named method whose parameter type matches the object type.
static Object	invokeMethod(Object object, String methodName, Object[] args, Class[] parameterTypes) Invoke a named method whose parameter type matches the object type.
static Object	invokeStaticMethod(Class cls, String methodName, Object arg) Invoke a named static method whose parameter type matches the object type.
static Object	invokeStaticMethod(Class cls, String methodName, Object[] args) Invoke a named static method whose parameter type matches the object type.
static Object	invokeStaticMethod(Class cls, String methodName, Object[] args, Class[] parameterTypes) Invoke a named static method whose parameter type matches the object type.

Methods inherited from class java.lang.Object

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

Constructor Detail

MethodUtils

public MethodUtils()

MethodUtils instances should NOT be constructed in standard programming. Instead, the class should be used as MethodUtils.getAccessibleMethod(method).

This constructor is public to permit tools that require a JavaBean instance to operate.

Method Detail

invokeMethod

public static Object invokeMethod(Object object,
                                  String methodName,
                                  Object arg)
                           throws NoSuchMethodException,
                                  IllegalAccessException,
                                  InvocationTargetException

Invoke a named method whose parameter type matches the object type.

This method delegates the method search to getMatchingAccessibleMethod(Class, String, Class[]).

This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean object would match a boolean primitive.

This is a convenient wrapper for invokeMethod(Object object, String methodName, Object[] args).

Parameters:

object - invoke method on this object

methodName - get method with this name

arg - use this argument

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeMethod

public static Object invokeMethod(Object object,
                                  String methodName,
                                  Object[] args)
                           throws NoSuchMethodException,
                                  IllegalAccessException,
                                  InvocationTargetException

Invoke a named method whose parameter type matches the object type.

This method delegates the method search to getMatchingAccessibleMethod(Class, String, Class[]).

This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean object would match a boolean primitive.

This is a convenient wrapper for invokeMethod(Object object,String methodName, Object[] args, Class[] parameterTypes).

Parameters:

object - invoke method on this object

methodName - get method with this name

args - use these arguments - treat null as empty array

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeMethod

public static Object invokeMethod(Object object,
                                  String methodName,
                                  Object[] args,
                                  Class[] parameterTypes)
                           throws NoSuchMethodException,
                                  IllegalAccessException,
                                  InvocationTargetException

Invoke a named method whose parameter type matches the object type.

This method delegates the method search to getMatchingAccessibleMethod(Class, String, Class[]).

This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean object would match a boolean primitive.

Parameters:

object - invoke method on this object

methodName - get method with this name

args - use these arguments - treat null as empty array

parameterTypes - match these parameters - treat null as empty array

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeExactMethod

public static Object invokeExactMethod(Object object,
                                       String methodName,
                                       Object arg)
                                throws NoSuchMethodException,
                                       IllegalAccessException,
                                       InvocationTargetException

Invoke a method whose parameter type matches exactly the object type.

This is a convenient wrapper for invokeExactMethod(Object object,String methodName,Object [] args).

Parameters:

object - invoke method on this object

methodName - get method with this name

arg - use this argument

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeExactMethod

public static Object invokeExactMethod(Object object,
                                       String methodName,
                                       Object[] args)
                                throws NoSuchMethodException,
                                       IllegalAccessException,
                                       InvocationTargetException

Invoke a method whose parameter types match exactly the object types.

This uses reflection to invoke the method obtained from a call to getAccessibleMethod().

Parameters:

object - invoke method on this object

methodName - get method with this name

args - use these arguments - treat null as empty array

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeExactMethod

public static Object invokeExactMethod(Object object,
                                       String methodName,
                                       Object[] args,
                                       Class[] parameterTypes)
                                throws NoSuchMethodException,
                                       IllegalAccessException,
                                       InvocationTargetException

Invoke a method whose parameter types match exactly the parameter types given.

This uses reflection to invoke the method obtained from a call to getAccessibleMethod().

Parameters:

object - invoke method on this object

methodName - get method with this name

args - use these arguments - treat null as empty array

parameterTypes - match these parameters - treat null as empty array

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeExactStaticMethod

public static Object invokeExactStaticMethod(Class cls,
                                             String methodName,
                                             Object[] args,
                                             Class[] parameterTypes)
                                      throws NoSuchMethodException,
                                             IllegalAccessException,
                                             InvocationTargetException

Invoke a static method whose parameter types match exactly the parameter types given.

This uses reflection to invoke the method obtained from a call to getAccessibleMethod(Class, String, Class[]).

Parameters:

cls - invoke static method on this class

methodName - get method with this name

args - use these arguments - treat null as empty array

parameterTypes - match these parameters - treat null as empty array

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeStaticMethod

public static Object invokeStaticMethod(Class cls,
                                        String methodName,
                                        Object arg)
                                 throws NoSuchMethodException,
                                        IllegalAccessException,
                                        InvocationTargetException

Invoke a named static method whose parameter type matches the object type.

This method delegates the method search to getMatchingAccessibleMethod(Class, String, Class[]).

This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

This is a convenient wrapper for invokeStaticMethod(Class objectClass,String methodName,Object [] args).

Parameters:

cls - invoke static method on this class

methodName - get method with this name

arg - use this argument

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeStaticMethod

public static Object invokeStaticMethod(Class cls,
                                        String methodName,
                                        Object[] args)
                                 throws NoSuchMethodException,
                                        IllegalAccessException,
                                        InvocationTargetException

Invoke a named static method whose parameter type matches the object type.

This method delegates the method search to getMatchingAccessibleMethod(Class, String, Class[]).

This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

This is a convenient wrapper for invokeStaticMethod(Class objectClass,String methodName,Object [] args,Class[] parameterTypes).

Parameters:

cls - invoke static method on this class

methodName - get method with this name

args - use these arguments - treat null as empty array

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeStaticMethod

public static Object invokeStaticMethod(Class cls,
                                        String methodName,
                                        Object[] args,
                                        Class[] parameterTypes)
                                 throws NoSuchMethodException,
                                        IllegalAccessException,
                                        InvocationTargetException

Invoke a named static method whose parameter type matches the object type.

This method delegates the method search to getMatchingAccessibleMethod(Class, String, Class[]).

This method supports calls to methods taking primitive parameters via passing in wrapping classes. So, for example, a Boolean class would match a boolean primitive.

Parameters:

cls - invoke static method on this class

methodName - get method with this name

args - use these arguments - treat null as empty array

parameterTypes - match these parameters - treat null as empty array

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeExactStaticMethod

public static Object invokeExactStaticMethod(Class cls,
                                             String methodName,
                                             Object arg)
                                      throws NoSuchMethodException,
                                             IllegalAccessException,
                                             InvocationTargetException

Invoke a static method whose parameter type matches exactly the object type.

This is a convenient wrapper for invokeExactStaticMethod(Class objectClass,String methodName,Object [] args).

Parameters:

cls - invoke static method on this class

methodName - get method with this name

arg - use this argument

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

invokeExactStaticMethod

public static Object invokeExactStaticMethod(Class cls,
                                             String methodName,
                                             Object[] args)
                                      throws NoSuchMethodException,
                                             IllegalAccessException,
                                             InvocationTargetException

Invoke a static method whose parameter types match exactly the object types.

This uses reflection to invoke the method obtained from a call to getAccessibleMethod(Class, String, Class[]).

Parameters:

cls - invoke static method on this class

methodName - get method with this name

args - use these arguments - treat null as empty array

Returns:

The value returned by the invoked method

Throws:

NoSuchMethodException - if there is no such accessible method

InvocationTargetException - wraps an exception thrown by the method invoked

IllegalAccessException - if the requested method is not accessible via reflection

getAccessibleMethod

public static Method getAccessibleMethod(Class cls,
                                         String methodName,
                                         Class parameterType)

Return an accessible method (that is, one that can be invoked via reflection) with given name and a single parameter. If no such method can be found, return null. Basically, a convenience wrapper that constructs a Class array for you.

Parameters:

cls - get method from this class

methodName - get method with this name

parameterType - taking this type of parameter

Returns:

The accessible method

getAccessibleMethod

public static Method getAccessibleMethod(Class cls,
                                         String methodName,
                                         Class[] parameterTypes)

Return an accessible method (that is, one that can be invoked via reflection) with given name and parameters. If no such method can be found, return null. This is just a convenient wrapper for getAccessibleMethod(Method method).

Parameters:

cls - get method from this class

methodName - get method with this name

parameterTypes - with these parameters types

Returns:

The accessible method

getAccessibleMethod

public static Method getAccessibleMethod(Method method)

Return an accessible method (that is, one that can be invoked via reflection) that implements the specified Method. If no such method can be found, return null.

Parameters:

method - The method that we wish to call

Returns:

The accessible method

getMatchingAccessibleMethod

public static Method getMatchingAccessibleMethod(Class cls,
                                                 String methodName,
                                                 Class[] parameterTypes)

Find an accessible method that matches the given name and has compatible parameters. Compatible parameters mean that every method parameter is assignable from the given parameters. In other words, it finds a method with the given name that will take the parameters given.

This method is used by invokeMethod(Object object, String methodName, Object[] args, Class[] parameterTypes).

This method can match primitive parameter by passing in wrapper classes. For example, a Boolean will match a primitive boolean parameter.

Parameters:

cls - find method in this class

methodName - find method with this name

parameterTypes - find method with most compatible parameters

Returns:

The accessible method