objectcreator.java

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package com.jdev.util;

import java.lang.reflect.*;

/**
 * Creates instance of any object, given its full qualified class name is given
 * and it has a public accessable constructor. This class is a static class it
 * can not be instantiated
 * @author Nadia Nashi
 */

public final class ObjectCreator {
	/**
	 * Private constructor. This class can not be instantiated
	 */
	private ObjectCreator() {
	}

	/**
	 * Instantaite an Object from a given class name
	 * @param className full qualified name of the class
	 * @return the instantaited Object
	 * @exception java.lang.Exception if instantiation failed
	 */
	public static Object createObject(String className) throws Exception {
		return createObject(Class.forName(className));
	}

	/**
	 * Instantaite an Object instance
	 * @param classObject Class object representing the object type to be instantiated
	 * @return the instantaied Object
	 * @exception java.lang.Exception if instantiation failed
	 */
	public static Object createObject(Class classObject) throws Exception {
		Object object = null;
		return classObject.newInstance();
	}

	/**
	 * Instantaite an Object instance, requires a constructor with parameters
	 * @param className full qualified name of the class
	 * @param params an array including the required parameters to instantaite the object
	 * @return the instantaited Object
	 * @exception java.lang.Exception if instantiation failed
	 */
	public static Object createObject(String className, Object[] params)
			throws Exception {
		return createObject(Class.forName(className), params);
	}

	/**
	 * Instantaite an Object instance, requires a constractor with parameters
	 * @param classObject, Class object representing the object type to be instantiated
	 * @param params an array including the required parameters to instantaite the object
	 * @return the instantaied Object
	 * @exception java.lang.Exception if instantiation failed
	 */
	public static Object createObject(Class classObject, Object[] params)
			throws Exception {
		Constructor[] constructors = classObject.getConstructors();
		Object object = null;
		for (int counter = 0; counter < constructors.length; counter++) {
			try {
				object = constructors[counter].newInstance(params);
			} catch (Exception e) {
				if (e instanceof InvocationTargetException)
					((InvocationTargetException) e).getTargetException()
							.printStackTrace();
				//do nothing, try the next constructor
			}
		}
		if (object == null)
			throw new InstantiationException();
		return object;
	}
}