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