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JavaUtil is a utility library to speed the development of Java software. We developed it over multiple years during our internal development efforts, and it has reached a point of stability where we have decided to make it available to the outside world. The JavaUtil package aims to fill in the gaps of the Apache Commons and similar utility libraries out there. Features include convenience classes for string, collections, arrays, dates, iterators, colors, logging, unit testing, a little bit of basic statistics, database queries, caching and more.

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/*
 * #%L
 * JavaUtil
 * %%
 * Copyright (C) 2012 - 2013 Emory University
 * %%
 * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
 * 
 * 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.
 * #L%
 */
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package org.arp.javautil.collections;

import java.io.Serializable;
import java.util.AbstractSequentialList;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.ListIterator;

/**
 *
 * @author Andrew Post
 */
public class CompositeList extends AbstractSequentialList implements Serializable {

    private final Collection> collOfLists;

    public CompositeList() {
        this(new ArrayList>(0));
    }

    public CompositeList(Collection> collOfLists) {
        if (collOfLists != null) {
            for (List list : collOfLists) {
                if (list == null) {
                    throw new IllegalArgumentException(
                            "Cannot have any null lists");
                }
            }
            this.collOfLists = new ArrayList<>(collOfLists);
        } else {
            this.collOfLists = new ArrayList<>();
        }
        
    }

    public void addList(List list) {
        this.collOfLists.add(list);
    }

    @Override
    public ListIterator listIterator(int i) {
        return new CompositeListIterator(i);
    }

    @Override
    public int size() {
        int result = 0;
        for (List list : this.collOfLists) {
            result += list.size();
        }
        return result;
    }

    private class CompositeListIterator implements ListIterator {

        private List> itrs;
        private int itrsIndex;
        private int itrsSize;
        private ListIterator currentItr;
        private int index;

        private CompositeListIterator(int i) {
            this.itrs = new ArrayList<>(CompositeList.this.collOfLists.size());
            for (List list : CompositeList.this.collOfLists) {
                itrs.add(list.listIterator());
            }
            this.index = 0;
            if (!itrs.isEmpty()) {
                this.currentItr = itrs.get(0);
            }
            this.itrsIndex = 0;
            this.itrsSize = this.itrs.size();
            while (this.index < i) {
                next();
            }
        }

        @Override
        public boolean hasNext() {
            boolean result = this.currentItr != null ? this.currentItr.hasNext() : false;
            int i = this.itrsIndex;
            while (!result && i < this.itrsSize - 1) {
                ListIterator next = this.itrs.get(++i);
                result = next.hasNext();
            }
            return result;
        }

        @Override
        @SuppressWarnings("unchecked")
        public E next() {
            boolean hasNext = this.currentItr != null ? this.currentItr.hasNext() : false;
            while (!hasNext && this.itrsIndex < this.itrsSize - 1) {
                this.currentItr = this.itrs.get(++this.itrsIndex);
                hasNext = this.currentItr.hasNext();
            }
            E nextElt = this.currentItr.next();
            this.index++;
            return nextElt;
        }

        @Override
        public boolean hasPrevious() {
            if (this.currentItr == null) {
                return false;
            }
            boolean result = this.currentItr.hasPrevious();
            ListIterator prev;
            int i = this.itrsIndex;
            while (!result && i > 0) {
                prev = this.itrs.get(--i);
                result = prev.hasPrevious();
            }
            return result;
        }

        @Override
        public E previous() {
            boolean hasPrev = this.currentItr != null ? this.currentItr.hasPrevious() : false;
            while (!hasPrev && this.itrsIndex > 0) {
                this.currentItr = this.itrs.get(--this.itrsIndex);
                hasPrev = this.currentItr.hasPrevious();
            }
            E prevElt = this.currentItr.previous();
            this.index--;
            return prevElt;
        }

        @Override
        public int nextIndex() {
            return this.currentItr != null ? this.index + 1 : 0;
        }

        @Override
        public int previousIndex() {
            return this.index - 1;
        }

        @Override
        public void remove() {
            throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public void set(E e) {
            throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public void add(E e) {
            throw new UnsupportedOperationException("Not supported yet.");
        }
    }
}