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package org.apache.commons.collections.list;

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

import org.apache.commons.collections.Predicate;
import org.apache.commons.collections.collection.PredicatedCollection;
import org.apache.commons.collections.iterators.AbstractListIteratorDecorator;

Decorates another List to validate that all additions match a specified predicate.

This list exists to provide validation for the decorated list. It is normally created to decorate an empty list. If an object cannot be added to the list, an IllegalArgumentException is thrown.

One usage would be to ensure that no null entries are added to the list.

List list = PredicatedList.decorate(new ArrayList(), NotNullPredicate.INSTANCE);

This class is Serializable from Commons Collections 3.1.

Author:Stephen Colebourne, Paul Jack
Since:Commons Collections 3.0
Version:$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
/** * Decorates another <code>List</code> to validate that all additions * match a specified predicate. * <p> * This list exists to provide validation for the decorated list. * It is normally created to decorate an empty list. * If an object cannot be added to the list, an IllegalArgumentException is thrown. * <p> * One usage would be to ensure that no null entries are added to the list. * <pre>List list = PredicatedList.decorate(new ArrayList(), NotNullPredicate.INSTANCE);</pre> * <p> * This class is Serializable from Commons Collections 3.1. * * @since Commons Collections 3.0 * @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $ * * @author Stephen Colebourne * @author Paul Jack */
public class PredicatedList extends PredicatedCollection implements List {
Serialization version
/** Serialization version */
private static final long serialVersionUID = -5722039223898659102L;
Factory method to create a predicated (validating) list.

If there are any elements already in the list being decorated, they are validated.

Params:
  • list – the list to decorate, must not be null
  • predicate – the predicate to use for validation, must not be null
Throws:
/** * Factory method to create a predicated (validating) list. * <p> * If there are any elements already in the list being decorated, they * are validated. * * @param list the list to decorate, must not be null * @param predicate the predicate to use for validation, must not be null * @throws IllegalArgumentException if list or predicate is null * @throws IllegalArgumentException if the list contains invalid elements */
public static List decorate(List list, Predicate predicate) { return new PredicatedList(list, predicate); } //-----------------------------------------------------------------------
Constructor that wraps (not copies).

If there are any elements already in the list being decorated, they are validated.

Params:
  • list – the list to decorate, must not be null
  • predicate – the predicate to use for validation, must not be null
Throws:
/** * Constructor that wraps (not copies). * <p> * If there are any elements already in the list being decorated, they * are validated. * * @param list the list to decorate, must not be null * @param predicate the predicate to use for validation, must not be null * @throws IllegalArgumentException if list or predicate is null * @throws IllegalArgumentException if the list contains invalid elements */
protected PredicatedList(List list, Predicate predicate) { super(list, predicate); }
Gets the list being decorated.
Returns:the decorated list
/** * Gets the list being decorated. * * @return the decorated list */
protected List getList() { return (List) getCollection(); } //----------------------------------------------------------------------- public Object get(int index) { return getList().get(index); } public int indexOf(Object object) { return getList().indexOf(object); } public int lastIndexOf(Object object) { return getList().lastIndexOf(object); } public Object remove(int index) { return getList().remove(index); } //----------------------------------------------------------------------- public void add(int index, Object object) { validate(object); getList().add(index, object); } public boolean addAll(int index, Collection coll) { for (Iterator it = coll.iterator(); it.hasNext(); ) { validate(it.next()); } return getList().addAll(index, coll); } public ListIterator listIterator() { return listIterator(0); } public ListIterator listIterator(int i) { return new PredicatedListIterator(getList().listIterator(i)); } public Object set(int index, Object object) { validate(object); return getList().set(index, object); } public List subList(int fromIndex, int toIndex) { List sub = getList().subList(fromIndex, toIndex); return new PredicatedList(sub, predicate); }
Inner class Iterator for the PredicatedList
/** * Inner class Iterator for the PredicatedList */
protected class PredicatedListIterator extends AbstractListIteratorDecorator { protected PredicatedListIterator(ListIterator iterator) { super(iterator); } public void add(Object object) { validate(object); iterator.add(object); } public void set(Object object) { validate(object); iterator.set(object); } } }