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Java > Open Source Codes > de > susebox > java > lang > Environment


1 /*
2  * Environment.java: Alternative System interface.
3  *
4  * Copyright (C) 2002 Heiko Blau
5  *
6  * This file belongs to the Susebox Java Core Library (Susebox JCL).
7  * The Susebox JCL is free software; you can redistribute it and/or modify it
8  * under the terms of the GNU Lesser General Public License as published by the
9  * Free Software Foundation; either version 2.1 of the License, or (at your
10  * option) any later version.
11  *
12  * This software is distributed in the hope that it will be useful, but WITHOUT
13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14  * FITNESS FOR A PARTICULAR PURPOSE.
15  * See the GNU Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public License along
18  * with the Susebox JCL. If not, write to the
19  *
20  * Free Software Foundation, Inc.
21  * 59 Temple Place, Suite 330,
22  * Boston, MA 02111-1307
23  * USA
24  *
25  * or check the Internet: http://www.fsf.org
26  *
27  * Contact:
28  * email: heiko@susebox.de
29  */
30
31 package de.susebox.java.lang;
32
33 //-----------------------------------------------------------------------------
34 // Imports
35 //
36 import java.io.InputStream JavaDoc;
37 import java.io.PrintStream JavaDoc;
38
39
40 //-----------------------------------------------------------------------------
41 // Interface Environment
42 //
43
44 /**<p>
45  * A <code>Environment</code> object is a substitute for the usual environment
46  * as defined in the {@link java.lang.System} class, most important the
47  * <code>stdin</code> and <code>stdout</code> channels {@link java.lang.System#in}
48  * and {@link java.lang.System#out}.
49  *</p><p>
50  * Environments are especially useful in classes that can be used both standalone
51  * (having a <code>main</code> method) or in an application where the class is
52  * only one of many. Another scenario would be a simple class designed for use
53  * from the command line that should suddenly be invoked in GUI framework without
54  * redirecting the default channels {@link java.lang.System#in} and
55  * {@link java.lang.System#out}.
56  *</p><p>
57  * To obtain an <code>Environment</code> instance or to store such instances
58  * use the class {@link EnvironmentProvider}:
59  *<block><pre>
60  * Environment env = EnvironmentProvider.getEnvironment(this);
61  *</pre></block>
62  *</p>
63  *
64  * @author Heiko Blau
65  */
66 public interface Environment {
67   
68   /**
69    * This method returns the substitution for {@link java.lang.System#in}, the
70    * standard input channel. Instead of a public member like in the <code>System</code>
71    * class, we prefer the method version since it is more flexible.
72    *
73    * @return the {@link java.io.InputStream} that serves as standard input
74    * @throws UnsupportedOperationException if there is no stdin channel available
75    * @see java.lang.System#in
76    */
77   public InputStream JavaDoc in() throws UnsupportedOperationException JavaDoc;
78   /*-->
79   {
80     throw UnsupportedOperationException;
81   }
82   -->*/
83   
84   /**
85    * This method returns the substitution for {@link java.lang.System#out}, the
86    * standard output channel. Instead of a public member like in the <code>System</code>
87    * class, we prefer the method version since it is more flexible.
88    *
89    * @return the {@link java.io.PrintStream} that serves as standard output
90    * @throws UnsupportedOperationException if there is no stdout channel available
91    * @see java.lang.System#out
92    */
93   public PrintStream JavaDoc out() throws UnsupportedOperationException JavaDoc;
94   /*-->
95   {
96     throw UnsupportedOperationException;
97   }
98   -->*/
99   
100   /**
101    * This method returns the substitution for {@link java.lang.System#err}, the
102    * standard error channel. Instead of a public member like in the <code>System</code>
103    * class, we prefer the method version since it is more flexible.
104    *
105    * @return the {@link java.io.PrintStream} that serves as standard error output
106    * @throws UnsupportedOperationException if there is no stderr channel available
107    * @see java.lang.System#err
108    */
109   public PrintStream JavaDoc err() throws UnsupportedOperationException JavaDoc;
110   /*-->
111   {
112     throw UnsupportedOperationException;
113   }
114   -->*/
115   
116   /**
117    * During different stages of program execution various exit codes can be set
118    * using this method. For instance, a program may set the exit code to a positive
119    * number indicating that it is still running. A negative exit code may stand
120    * for errors while 0 is the usual OK code.
121    *
122    * @param status the exit code of an application
123    * @see java.lang.System#exit
124    * @see #getExitStatus
125    * @see #exit
126    */
127   public void setExitStatus(int status);
128   /*-->
129   {
130     _exitStatus = status;
131   }
132   -->*/
133   
134   /**
135    * Retrieving the currently set exit code.
136    *
137    * @return the currently set exit code of an application
138    */
139   public int getExitStatus();
140   /*-->
141   {
142     return _exitStatus;
143   }
144   -->*/
145
146
147   /**
148    * This method exits the instance of its <code>Environment</code> implementation.
149    * After calling <code>exit</code> the <code>Environment</code> instance is
150    * generally not any longer usable. In particular, an implementation can choose
151    * to call {@link java.lang.System#exit}.
152    *
153    * @throws UnsupportedOperationException if the method is not available
154    * @see #setExitStatus
155    * @see java.lang.System#exit
156    */
157   public void exit() throws UnsupportedOperationException JavaDoc;
158   /*-->
159   {
160     throw UnsupportedOperationException;
161   }
162   -->*/
163   
164   
165   //---------------------------------------------------------------------------
166 // members
167 //
168 /*-->
169   private int _exitStatus = 0;
170   -->*/
171 }
172
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