ListOfLists.java Source code

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Here is the source code for ListOfLists.java

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/*
 * $Id: ListOfLists.java,v 1.1.1.1 2005/04/07 18:36:24 pocho Exp $
 */

import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

/**
 * Creates list containing other lists, access another list's elements as it would belong
 * to this list. 
 * 
 * @version $Name:  $ - $Revision: 1.1.1.1 $ - $Date: 2005/04/07 18:36:24 $
 * TODO Test
 */
public class ListOfLists extends AbstractList {
    private Collection lists = new ArrayList();

    public ListOfLists(Collection c) {
        Iterator it = c.iterator();
        Object o;
        while (it.hasNext()) {
            o = it.next();
            if (o instanceof List)
                lists.add(o);
            else if (o != null)
                throw new UnsupportedOperationException(this.getClass().getName()
                        + " class supports only instances " + "of java.util.List interface");
        }
    }

    public int size() {
        Iterator it = lists.iterator();
        int size = 0;
        Object o;
        while (it.hasNext()) {
            o = it.next();
            if (o != null)
                size += ((List) o).size();
        }
        return size;
    }

    public Object get(int index) {
        int size = size();
        if (index < 0)
            throw new IndexOutOfBoundsException("index: " + index + "; size: " + size);

        Iterator it = lists.iterator();
        while (it.hasNext()) {
            List list = (List) it.next();
            if (index < list.size()) {
                return list.get(index);
            } else
                index -= list.size();
        }

        // if value has not been returned yet - IndexOutOfBoundsException is thrown
        throw new IndexOutOfBoundsException("index: " + index + "; size: " + size);
    }

    /**
     * Replaces the element at the specified position in underlying list with the
     * specified element.
     *
     * @param index index of element to replace.
     * @param element element to be stored at the specified position.
     * @return the element previously at the specified position.
     */
    public Object set(int index, Object element) {
        int size = size();
        if (index < 0)
            throw new IndexOutOfBoundsException("index: " + index + "; size: " + size);

        Iterator it = lists.iterator();
        while (it.hasNext()) {
            List list = (List) it.next();
            if (index < list.size()) {
                return list.set(index, element);
            } else
                index -= list.size();
        }

        // if value has not been returned yet - IndexOutOfBoundsException is thrown
        throw new IndexOutOfBoundsException("index: " + index + "; size: " + size);
    }

    public int indexOf(Object o) {
        ListIterator e = listIterator();
        if (o == null) {
            while (e.hasNext()) {
                if (e.next() == null)
                    return e.previousIndex();
            }
        } else {
            Object el;
            while (e.hasNext()) {
                el = e.next();
                if (el.equals(o))
                    return e.previousIndex();
            }
        }
        return -1;
    }

    public int lastIndexOf(Object o) {
        ListIterator e = listIterator(size());
        if (o == null) {
            while (e.hasPrevious()) {
                if (e.previous() == null)
                    return e.nextIndex();
            }
        } else {
            Object el;
            while (e.hasPrevious()) {
                el = e.previous();
                if (el != null && el.equals(o))
                    return e.nextIndex();
            }
        }
        return -1;
    }
}