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Java > Open Source Codes > com > eaio > nativecall > Holder


1 /*
2  * Holder.java
3  *
4  * Created on 14.09.2004.
5  *
6  * eaio: NativeCall - calling operating system methods from Java
7  * Copyright (c) 2004-2006 Johann Burkard (<mailto:jb@eaio.com>)
8  * <http://eaio.com>
9  *
10  * Permission is hereby granted, free of charge, to any person obtaining a
11  * copy of this software and associated documentation files (the "Software"),
12  * to deal in the Software without restriction, including without limitation
13  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
14  * and/or sell copies of the Software, and to permit persons to whom the
15  * Software is furnished to do so, subject to the following conditions:
16  *
17  * The above copyright notice and this permission notice shall be included
18  * in all copies or substantial portions of the Software.
19  *
20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
21  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
23  * NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
24  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
25  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
26  * USE OR OTHER DEALINGS IN THE SOFTWARE.
27  *
28  */
29 package com.eaio.nativecall;
30
31 /**
32  * Holder is a class that encapsulates another Object. Use this class for output
33  * parameters.
34  *
35  * @author <a HREF="mailto:jb@eaio.com">Johann Burkard</a>
36  * @version $Id: Holder.java,v 1.3 2006/04/19 20:54:58 grnull Exp $
37  */
38 public class Holder {
39
40     /**
41      * The encapsulated object.
42      * <p>
43      * Accessed by native code. DO NOT RENAME THIS FIELD.
44      */
45     private Object JavaDoc o;
46
47     /**
48      * Constructor for Holder.
49      *
50      * @param o the Object to encapsulate, may be <code>null</code>, but cannot
51      * be of type Holder
52      * @throws ClassCastException if o is of type Holder
53      */
54     public Holder(Object JavaDoc o) {
55         if (o instanceof Holder) {
56             throw new ClassCastException JavaDoc();
57         }
58         else if (o == null) {
59             o = new Integer JavaDoc(0);
60         }
61         this.o = o;
62     }
63
64     /**
65      * Returns the referenced Object.
66      *
67      * @return an Object
68      */
69     public final Object JavaDoc get() {
70         return o;
71     }
72
73     /**
74      * Returns the hashCode of the encapsulated Object or
75      * {@link java.lang.Object#hashCode()} if the Object is <code>null</code>.
76      *
77      * @return the hashCode
78      * @see java.lang.Object#hashCode()
79      */
80     public int hashCode() {
81         return getClass().getName().hashCode() ^ (o == null ? 0 : o.hashCode());
82     }
83
84     /**
85      * Returns if this Object is equal to another Object.
86      *
87      * @param obj the other Object, may be <code>null</code>
88      * @return if both Objects are equal
89      * @see java.lang.Object#equals(java.lang.Object)
90      */
91     public boolean equals(Object JavaDoc obj) {
92         if (this == obj) {
93             return true;
94         }
95         if (!(obj instanceof Holder)) {
96             return false;
97         }
98         Holder h = (Holder) obj;
99         return o == null ? h.o == null : o.equals(h.o);
100     }
101
102     /**
103      * Returns a String representation of this Object.
104      *
105      * @return a String, never <code>null</code>
106      * @see java.lang.Object#toString()
107      * @see #toStringBuffer(StringBuffer)
108      */
109     public final String JavaDoc toString() {
110         return toStringBuffer(null).toString();
111     }
112
113     /**
114      * Appends a String representation of this Object to the given
115      * {@link StringBuffer} or creates a new one if none is given.
116      *
117      * @param in the StringBuffer to append to, may be <code>null</code>
118      * @return a StringBuffer, never <code>null</code>
119      */
120     public StringBuffer JavaDoc toStringBuffer(StringBuffer JavaDoc in) {
121         if (in == null) {
122             in = new StringBuffer JavaDoc(32);
123         }
124         else {
125             in.ensureCapacity(in.length() + 32);
126         }
127         in.append("{ Holder: o = ");
128         in.append(o);
129         in.append(" }");
130         return in;
131     }
132
133 }
134
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