Java Reflection Method Invoke invokeMethod(Method method, Object target, Object[] args)

Description

Invoke the specified Method against the supplied target object with the supplied arguments.

License

Open Source License

Declaration

public static Object invokeMethod(Method method, Object target, Object[] args) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {
    /**/*w  w  w.ja v a2 s.  c o  m*/
     * Invoke the specified {@link Method} against the supplied target object
     * with the supplied arguments. The target object can be <code>null</code>
     * when invoking a static {@link Method}.
     * <p>
     * Thrown exceptions are handled via a call to
     * {@link #handleReflectionException}.
     * 
     * @see #invokeMethod(java.lang.reflect.Method, Object, Object[])
     */
    public static Object invokeMethod(Method method, Object target, Object[] args) {
        try {
            return method.invoke(target, args);
        } catch (IllegalAccessException ex) {
            handleReflectionException(ex);
            throw new IllegalStateException(
                    "Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());
        } catch (InvocationTargetException ex) {
            handleReflectionException(ex);
            throw new IllegalStateException(
                    "Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());
        }
    }

    /**
     * Handle the given reflection exception. Should only be called if no
     * checked exception is expected to be thrown by the target method.
     * <p>
     * Throws the underlying RuntimeException or Error in case of an
     * InvocationTargetException with such a root cause. Throws an
     * IllegalStateException with an appropriate message else.
     * 
     * @param ex
     *            the reflection exception to handle
     */
    public static void handleReflectionException(Exception ex) {
        if (ex instanceof NoSuchMethodException) {
            throw new IllegalStateException("Method not found: " + ex.getMessage());
        }
        if (ex instanceof IllegalAccessException) {
            throw new IllegalStateException("Could not access method: " + ex.getMessage());
        }
        if (ex instanceof InvocationTargetException) {
            handleInvocationTargetException((InvocationTargetException) ex);
        }
        throw new IllegalStateException(
                "Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());
    }

    /**
     * Handle the given invocation target exception. Should only be called if no
     * checked exception is expected to be thrown by the target method.
     * <p>
     * Throws the underlying RuntimeException or Error in case of such a root
     * cause. Throws an IllegalStateException else.
     * 
     * @param ex
     *            the invocation target exception to handle
     */
    public static void handleInvocationTargetException(InvocationTargetException ex) {
        if (ex.getTargetException() instanceof RuntimeException) {
            throw (RuntimeException) ex.getTargetException();
        }
        if (ex.getTargetException() instanceof Error) {
            throw (Error) ex.getTargetException();
        }
        throw new IllegalStateException("Unexpected exception thrown by method - "
                + ex.getTargetException().getClass().getName() + ": " + ex.getTargetException().getMessage());
    }
}

Related

1. invokeMethod(Method method, Object target, Class expectedType)
2. invokeMethod(Method method, Object target, Object... args)
3. invokeMethod(Method method, Object target, Object... args)
4. invokeMethod(Method method, Object target, Object... arguments)
5. invokeMethod(Method method, Object target, Object... params)
6. invokeMethod(Method method, Object target, Object[] args)
7. invokeMethod(Method method, Object theObject, Object[] args)
8. invokeMethod(Method method, Object... arguments)
9. invokeMethod(Object bean, Method method, Object... param)