1 /*
   2  * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.awt;
  27 
  28 /**
  29  * Thrown when code that is dependent on a keyboard, display, or mouse
  30  * is called in an environment that does not support a keyboard, display,
  31  * or mouse.
  32  *
  33  * @since 1.4
  34  * @author  Michael Martak
  35  */
  36 public class HeadlessException extends UnsupportedOperationException {
  37     /*
  38      * JDK 1.4 serialVersionUID
  39      */
  40     private static final long serialVersionUID = 167183644944358563L;
  41 
  42     /**
  43      * Constructs new {@code HeadlessException}
  44      */
  45     public HeadlessException() {}
  46 
  47     /**
  48      * Create a new instance with the specified detailed error message.
  49      *
  50      * @param  msg the error message
  51      */
  52     public HeadlessException(String msg) {
  53         super(msg);
  54     }
  55 
  56     /**
  57      * {@inheritDoc}
  58      */
  59     public String getMessage() {
  60         String superMessage = super.getMessage();
  61         String headlessMessage = GraphicsEnvironment.getHeadlessMessage();
  62 
  63         if (superMessage == null) {
  64             return headlessMessage;
  65         } else if (headlessMessage == null) {
  66             return superMessage;
  67         } else {
  68             return superMessage + headlessMessage;
  69         }
  70     }
  71 }