1 /*
2 * $Source$
3 * $Revision$
4 *
5 * Copyright (C) 2000 William Chesters
6 *
7 * Part of Melati (http://melati.org), a framework for the rapid
8 * development of clean, maintainable web applications.
9 *
10 * Melati is free software; Permission is granted to copy, distribute
11 * and/or modify this software under the terms either:
12 *
13 * a) the GNU General Public License as published by the Free Software
14 * Foundation; either version 2 of the License, or (at your option)
15 * any later version,
16 *
17 * or
18 *
19 * b) any version of the Melati Software License, as published
20 * at http://melati.org
21 *
22 * You should have received a copy of the GNU General Public License and
23 * the Melati Software License along with this program;
24 * if not, write to the Free Software Foundation, Inc.,
25 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the
26 * GNU General Public License and visit http://melati.org to obtain the
27 * Melati Software License.
28 *
29 * Feel free to contact the Developers of Melati (http://melati.org),
30 * if you would like to work out a different arrangement than the options
31 * outlined here. It is our intention to allow Melati to be used by as
32 * wide an audience as possible.
33 *
34 * This program is distributed in the hope that it will be useful,
35 * but WITHOUT ANY WARRANTY; without even the implied warranty of
36 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
37 * GNU General Public License for more details.
38 *
39 * Contact details for copyright holder:
40 *
41 * William Chesters <williamc@paneris.org>
42 * http://paneris.org/~williamc
43 * Obrechtstraat 114, 2517VX Den Haag, The Netherlands
44 */
45
46 package org.melati.poem.util;
47
48 import java.util.Vector;
49 import java.util.Enumeration;
50
51 /**
52 * A collection of useful operations on <code>Array</code>s.
53 */
54 public final class ArrayUtils {
55
56 private ArrayUtils() {}
57
58 /**
59 * Create an Array from a Vector.
60 * @param v the Vector
61 * @return the Array
62 */
63 @SuppressWarnings("unchecked")
64 public static <T> T[] arrayOf(Vector<T> v) {
65 T[] arr;
66 synchronized (v) {
67 arr = (T[])new Object[v.size()];
68 v.copyInto(arr);
69 }
70 return arr;
71 }
72
73 /**
74 * Create an Array from an Enumeration.
75 * @param e the Enumeration
76 * @return the Array
77 */
78 public static Object[] arrayOf(Enumeration<Object> e) {
79 Vector<Object> v = EnumUtils.vectorOf(e);
80 return arrayOf(v);
81 }
82
83 /**
84 * Add an Object to an Array.
85 *
86 * @param xs the array to add to
87 * @param y the object to add
88 * @return the enlarged array
89 */
90 public static Object[] added(Object[] xs, Object y) {
91 Object[] xsx = (Object[])java.lang.reflect.Array.newInstance(
92 xs.getClass().getComponentType(), xs.length + 1);
93 System.arraycopy(xs, 0, xsx, 0, xs.length);
94 xsx[xs.length] = y;
95 return xsx;
96 }
97
98 /**
99 * Remove an Object from an Array.
100 *
101 * @param xs the array to remove from
102 * @param y the object to remove
103 * @return the reduced array
104 */
105 public static Object[] removed(Object[] xs, Object y) {
106 Object[] xsx = (Object[])java.lang.reflect.Array.newInstance(
107 xs.getClass().getComponentType(), xs.length - 1);
108 int j = 0;
109 for (int i = 0; i < xs.length; i++) {
110 if (xs[i] != y) {
111 xsx[j] = xs[i];
112 j++;
113 }
114 }
115 return xsx;
116 }
117
118 /**
119 * Create a new Array from two Arrays.
120 * @param xs first Array
121 * @param ys second Array
122 * @return a new Array with the elements of the second appended to the first
123 */
124 public static Object[] concatenated(Object[] xs, Object[] ys) {
125 Object[] xsys =
126 (Object[])java.lang.reflect.Array.newInstance(
127 xs.getClass().getComponentType(), xs.length + ys.length);
128 System.arraycopy(xs, 0, xsys, 0, xs.length);
129 System.arraycopy(ys, 0, xsys, xs.length, ys.length);
130 return xsys;
131 }
132
133 /**
134 * Extract a subsection of an Array.
135 *
136 * @param xs the input Array
137 * @param start the index in the original array to start our section, inclusive
138 * @param limit the index in the original array to stop at, inclusive
139 * @return the new Array
140 */
141 public static Object[] section(Object[] xs, int start, int limit) {
142 Object[] xs_ = (Object[])java.lang.reflect.Array.newInstance(
143 xs.getClass().getComponentType(), limit - start);
144 System.arraycopy(xs, start, xs_, 0, xs_.length);
145 return xs_;
146 }
147
148 /**
149 * Lookup the first instance of an Object in an Array.
150 *
151 * @param xs the Array to search
152 * @param x the Object to check
153 * @return the index of the first <code>equal</code> object
154 */
155 public static int indexOf(Object[] xs, Object x) {
156 for (int i = 0; i < xs.length; ++i)
157 if (xs[i].equals(x)) return i;
158 return -1;
159 }
160
161 /**
162 * Whether an Array contains an Object.
163 *
164 * @param xs the Array to search
165 * @param x the Object to check
166 * @return whether it is there or not
167 */
168 public static boolean contains(Object[] xs, Object x) {
169 return indexOf(xs, x) != -1;
170 }
171 }