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1   /*
2    * Copyright (c) 2010, 2013, 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 com.sun.tools.doclets.internal.toolkit;
27  
28  import java.io.IOException;
29  import java.io.StringWriter;
30  import java.io.Writer;
31  
32  import com.sun.tools.doclets.internal.toolkit.util.*;
33  
34  /**
35   * A class to create content for javadoc output pages.
36   *
37   *  <p><b>This is NOT part of any supported API.
38   *  If you write code that depends on this, you do so at your own risk.
39   *  This code and its internal interfaces are subject to change or
40   *  deletion without notice.</b>
41   *
42   * @author Bhavesh Patel
43   */
44  public abstract class Content {
45  
46      /**
47       * Returns a string representation of the content.
48       *
49       * @return string representation of the content
50       */
51      @Override
52      public String toString() {
53          StringWriter out = new StringWriter();
54          try {
55              write(out, true);
56          } catch (IOException e) {
57              // cannot happen from StringWriter
58              throw new DocletAbortException(e);
59          }
60          return out.toString();
61      }
62  
63      /**
64       * Adds content to the existing content.
65       *
66       * @param content content that needs to be added
67       */
68      public abstract void addContent(Content content);
69  
70      /**
71       * Adds a string content to the existing content.
72       *
73       * @param stringContent the string content to be added
74       */
75      public abstract void addContent(String stringContent);
76  
77      /**
78       * Writes content to a writer.
79       *
80       */
81      public abstract boolean write(Writer writer, boolean atNewline) throws IOException ;
82  
83      /**
84       * Returns true if the content is empty.
85       *
86       * @return true if no content to be displayed else return false
87       */
88      public abstract boolean isEmpty();
89  
90      /**
91       * Returns true if the content is valid.
92       *
93       * @return true if the content is valid else return false
94       */
95      public boolean isValid() {
96          return !isEmpty();
97      }
98  
99      /**
100      * Return the number of characters of plain text content in this object
101      * (optional operation.)
102      * @return the number of characters of plain text content in this
103      */
104     public int charCount() {
105         return 0;
106     }
107 
108     /**
109      * Checks for null values.
110      *
111      * @param t reference type to check for null values
112      * @return the reference type if not null or else throws a null pointer exception
113      */
114     protected static <T> T nullCheck(T t) {
115         t.getClass();
116         return t;
117     }
118 }