001: /*
002: * Primitive Collections for Java.
003: * Copyright (C) 2002, 2003 Søren Bak
004: *
005: * This library is free software; you can redistribute it and/or
006: * modify it under the terms of the GNU Lesser General Public
007: * License as published by the Free Software Foundation; either
008: * version 2.1 of the License, or (at your option) any later version.
009: *
010: * This library is distributed in the hope that it will be useful,
011: * but WITHOUT ANY WARRANTY; without even the implied warranty of
012: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
013: * Lesser General Public License for more details.
014: *
015: * You should have received a copy of the GNU Lesser General Public
016: * License along with this library; if not, write to the Free Software
017: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
018: */
019: package bak.pcj.adapter;
020:
021: import bak.pcj.Adapter;
022: import bak.pcj.list.AbstractDoubleList;
023: import bak.pcj.list.DoubleListIterator;
024: import bak.pcj.util.Exceptions;
025:
026: import java.util.List;
027:
028: /**
029: * This class represents adaptions of Java Collections Framework
030: * lists to primitive lists of double values.
031: * The adapter is implemented as a wrapper around the list.
032: * Thus, changes to the underlying list are reflected by this
033: * list and vice versa.
034: *
035: * <p>
036: * Adapters from JCF collections to primitive collections will
037: * fail if the JCF collection contains <tt>null</tt> values or
038: * values of the wrong class. However, adapters are not fast
039: * failing in the case that the underlying collection should
040: * contain illegal values. To implement fast failure would require
041: * every operation to check every element of the underlying
042: * collection before doing anything. Instead validation methods
043: * are provided. They can be called using the assertion facility
044: * in the client code:
045: * <pre>
046: * ListToDoubleListAdapter s;
047: * ...
048: * <b>assert</b> s.validate();
049: * </pre>
050: * or by letting the adapter throw an exception on illegal values:
051: * <pre>
052: * ListToDoubleListAdapter s;
053: * ...
054: * s.evalidate(); // Throws an exception on illegal values
055: * </pre>
056: * Either way, validation must be invoked directly by the client
057: * code.
058: *
059: * @author Søren Bak
060: * @version 1.2 20-08-2003 23:17
061: * @since 1.0
062: */
063: public class ListToDoubleListAdapter extends AbstractDoubleList {
064:
065: /** The underlying list. */
066: protected List list;
067:
068: /**
069: * Creates a new adaption of a list to a list of double
070: * values.
071: *
072: * @param list
073: * the underlying list. This list must
074: * consist of values of class
075: * {@link Double Double}. Otherwise a
076: * {@link ClassCastException ClassCastException}
077: * will be thrown by some methods.
078: *
079: * @throws NullPointerException
080: * if <tt>list</tt> is <tt>null</tt>.
081: */
082: public ListToDoubleListAdapter(List list) {
083: this (list, false);
084: }
085:
086: /**
087: * Creates a new adaption of a list to a list of double
088: * values. The list to adapt is optionally validated.
089: *
090: * @param list
091: * the underlying list. This collection must
092: * consist of values of class
093: * {@link Double Double}. Otherwise a
094: * {@link ClassCastException ClassCastException}
095: * will be thrown by some methods.
096: *
097: * @param validate
098: * indicates whether <tt>list</tt> should
099: * be checked for illegal values.
100: *
101: * @throws NullPointerException
102: * if <tt>list</tt> is <tt>null</tt>.
103: *
104: * @throws IllegalStateException
105: * if <tt>validate</tt> is <tt>true</tt> and
106: * <tt>list</tt> contains a <tt>null</tt> value
107: * or a value that is not of class
108: * {@link Double Double}.
109: */
110: public ListToDoubleListAdapter(List list, boolean validate) {
111: super ();
112: if (list == null)
113: Exceptions.nullArgument("list");
114: this .list = list;
115: if (validate)
116: evalidate();
117: }
118:
119: public void add(int index, double v) {
120: list.add(index, new Double(v));
121: }
122:
123: public double get(int index) {
124: return ((Double) list.get(index)).doubleValue();
125: }
126:
127: public DoubleListIterator listIterator(int index) {
128: return new ListIteratorToDoubleListIteratorAdapter(list
129: .listIterator(index));
130: }
131:
132: public double removeElementAt(int index) {
133: return ((Double) (list.remove(index))).doubleValue();
134: }
135:
136: public double set(int index, double v) {
137: return ((Double) list.set(index, new Double(v))).doubleValue();
138: }
139:
140: public int size() {
141: return list.size();
142: }
143:
144: /**
145: * Indicates whether the underlying list is valid for
146: * this adapter. For the underlying list to be valid, it
147: * can only contain {@link Double Double} values and no <tt>null</tt>
148: * values.
149: *
150: * @return <tt>true</tt> if the underlying list is
151: * valid; returns <tt>false</tt> otherwise.
152: */
153: public boolean validate() {
154: return Adapter.isDoubleAdaptable(list);
155: }
156:
157: /**
158: * Validates the list underlying this adapter and throws
159: * an exception if it is invalid. For the underlying list
160: * to be valid, it can only contain {@link Double Double}
161: * values and no <tt>null</tt> values.
162: *
163: * @throws IllegalStateException
164: * if the underlying list is invalid.
165: */
166: public void evalidate() {
167: if (!validate())
168: Exceptions.cannotAdapt("list");
169: }
170:
171: }
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