/*

  * Copyright 2005-2008 The Kuali Foundation

  * 

  * Licensed under the Educational Community License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  * 

  * http://www.opensource.org/licenses/ecl2.php

  * 

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.kuali.rice.kns.util;

 import java.beans.Beans;

 import java.lang.reflect.Constructor;

 import java.lang.reflect.Modifier;

 import java.util.ArrayList;

 import org.apache.commons.lang.ArrayUtils;

 /**

  * This class is used to maintain an ArrayList for a specified object type.

  * 

  * 

  */

 public class TypedArrayList extends ArrayList {

     private static final long serialVersionUID = 6238521951259126730L;

     private final Class listObjectType;

     public TypedArrayList(Class listObjectType) {

         super();

         if (listObjectType == null) {

             throw new RuntimeException("class type for list is required.");

         }

         //the following code checks to see if the class has a visible default constructor

         boolean foundDefaultConstructor = false;

         Constructor[] constructors = listObjectType.getConstructors();

         for (Constructor constructor : constructors) {

             Class[] parameterType = constructor.getParameterTypes();

             //check for a constructor that takes no arguments and is public

             if(ArrayUtils.isEmpty(parameterType) &&

                Modifier.isPublic(constructor.getModifiers())) {

                 foundDefaultConstructor = true;

                 break;

             }

         }

         if(!foundDefaultConstructor) {

             throw new RuntimeException("unable to get default constructor for " + listObjectType.getName());

         }

         this.listObjectType = listObjectType;

     }

     /**

      * @see java.util.List#add(int, java.lang.Object)

      */

     public void add(int index, Object element) {

         checkType(element);

         super.add(index, element);

     }

     /**

      * @see java.util.Collection#add(java.lang.Object)

      */

     public boolean add(Object o) {

         checkType(o);

         return super.add(o);

     }

     /**

      * @see java.util.List#get(int)

      */

     public Object get(int index) {

         growArray(index);

         return super.get(index);

     }

     /**

      * @see java.util.List#set(int, java.lang.Object)

      */

     public Object set(int index, Object element) {

         growArray(index);

         return super.set(index, element);

     }

     /**

      * Adds new instances of type listObjectType to the arraylist until the size of the list is greater than the index required.

      */

     private void growArray(int index) {

         if (index < 0) {

             throw new IndexOutOfBoundsException("Index must be positive.");

         }

         // ensureCapacity(index); // Increments modCount

         while (size() <= index) {

             try {

                 super.add(listObjectType.newInstance());

             }

             catch (InstantiationException e) {

                 throw new RuntimeException("Cannot get new instance of class " + listObjectType.getName());

             }

             catch (IllegalAccessException e) {

                 throw new RuntimeException("Cannot get new instance of class " + listObjectType.getName());

             }

         }

     }

     /**

      * Checks the type of an element matches the underlying list type.

      */

     private void checkType(Object element) {

         if (element != null) {

             if (!Beans.isInstanceOf(element, listObjectType)) {

                 throw new RuntimeException("element is not of correct type.");

             }

         }

     }

     /**

      * @return Returns the listObjectType.

      */

     public Class getListObjectType() {

         return listObjectType;

     }

 }