package com.alexrnl.commons.utils.object;

import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Utilities methods for reflection and dynamic Java usage.<br />
 * @author Alex
 */
public final class ReflectUtils {
	/** Logger */
	private static Logger	lg	= Logger.getLogger(ReflectUtils.class.getName());
	
	/**
	 * Constructor #1.<br />
	 * Private default constructor.
	 */
	private ReflectUtils () {
		super();
	}
	
	/**
	 * Retrieve the methods for the class marked with the specified annotation.<br />
	 * @param objClass
	 *        the class to parse.
	 * @param annotationClass
	 *        the annotation to find.
	 * @return a {@link Set} with the {@link Method} annotated with <code>annotationClass</code>.
	 * @see Class#getMethods()
	 */
	public static Set<Method> retrieveMethods (final Class<?> objClass, final Class<? extends Annotation> annotationClass) {
		final Set<Method> fieldMethods = new HashSet<>();
		for (final Method method : objClass.getMethods()) {
			final Annotation annotation = method.getAnnotation(annotationClass);
			if (annotationClass == null || annotation != null) {
				if (lg.isLoggable(Level.FINE)) {
					lg.fine("Added method: " + method.getName());
				}
				fieldMethods.add(method);
			}
		}
		return fieldMethods;
	}
	
	/**
	 * Invoke the following list of methods (with no parameter) and return the result in a
	 * {@link List}.
	 * @param target
	 *        the target object.
	 * @param methods
	 *        the methods to invoke.
	 * @return the result of the method call.
	 * @throws InvocationTargetException
	 *         if the underlying method throws an exception
	 * @throws IllegalArgumentException
	 *         if the method is an instance method and the specified object argument is not an
	 *         instance of the class or interface declaring the underlying method (or of a subclass
	 *         or implementor thereof); if the number of actual and formal parameters differ; if an
	 *         unwrapping conversion for primitive arguments fails; or if, after possible
	 *         unwrapping, a parameter value cannot be converted to the corresponding formal
	 *         parameter type by a method invocation conversion.
	 * @throws IllegalAccessException
	 *         if this Method object is enforcing Java language access control and the underlying
	 *         method is inaccessible.
	 */
	public static List<Object> invokeMethods (final Object target, final List<Method> methods)
			throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
		final List<Object> results = new ArrayList<>(methods.size());
		
		for (final Method method : methods) {
			results.add(method.invoke(target, (Object[]) null));
		}
		
		return results;
	}
}

package com.alexrnl.commons.utils.object;

import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Utilities methods for reflection and dynamic Java usage.<br />
 * @author Alex
 */
public final class ReflectUtils {
	/** Logger */
	private static Logger	lg	= Logger.getLogger(ReflectUtils.class.getName());
	
	/**
	 * Constructor #1.<br />
	 * Private default constructor.
	 */
	private ReflectUtils () {
		super();
	}
	
	/**
	 * Retrieve the methods for the class marked with the specified annotation.<br />
	 * @param objClass
	 *        the class to parse.
	 * @param annotationClass
	 *        the annotation to find.
	 * @return a {@link Set} with the {@link Method} annotated with <code>annotationClass</code>.
	 * @see Class#getMethods()
	 */
	public static Set<Method> retrieveMethods (final Class<?> objClass, final Class<? extends Annotation> annotationClass) {
		final Set<Method> fieldMethods = new HashSet<>();
		for (final Method method : objClass.getMethods()) {
			final Annotation annotation = method.getAnnotation(annotationClass);
			if (annotationClass == null || annotation != null) {
				if (lg.isLoggable(Level.FINE)) {
					lg.fine("Added method: " + method.getName());
				}
				fieldMethods.add(method);
			}
		}
		return fieldMethods;
	}
	
	/**
	 * Invoke the following list of methods (with no parameter) and return the result in a
	 * {@link List}.
	 * @param target
	 *        the target object.
	 * @param methods
	 *        the methods to invoke.
	 * @return the result of the method call.
	 * @throws InvocationTargetException
	 *         if one of the underlying method throws an exception
	 * @throws IllegalArgumentException
	 *         if the method is an instance method and the specified object argument is not an
	 *         instance of the class or interface declaring the underlying method (or of a subclass
	 *         or implementor thereof); if the number of actual and formal parameters differ; if an
	 *         unwrapping conversion for primitive arguments fails; or if, after possible
	 *         unwrapping, a parameter value cannot be converted to the corresponding formal
	 *         parameter type by a method invocation conversion.
	 * @throws IllegalAccessException
	 *         if one of the Method object is enforcing Java language access control and the underlying
	 *         method is inaccessible.
	 */
	public static List<Object> invokeMethods (final Object target, final List<Method> methods)
			throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
		final List<Object> results = new ArrayList<>(methods.size());
		
		for (final Method method : methods) {
			results.add(method.invoke(target, (Object[]) null));
		}
		
		return results;
	}
}

Correct Javadoc