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Java 现场上课
现场上课
实例源码：
源代码：
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import java.lang.reflect.Field;/*时代Java 提供*/3
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import java.util.Arrays;5
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import static java.lang.System.out;7
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enum Tweedle {10
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DEE, DUM12
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}14
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public class Book {17
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public long chapters = 0;19
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public String[] characters = { "Alice", "White Rabbit" };21
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public Tweedle twin = Tweedle.DEE;23
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public static void main(String args) {26
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Book book = new Book();28
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String fmt = "%6S: %-12s = %s%n";/* 来 自 时代Java公众号*/30
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try {33
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Class<?> c = book.getClass();35
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Field chap = c.getDeclaredField("chapters");38
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out.format(fmt, "before", "chapters", book.chapters);40
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chap.setLong(book, 12);42
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out.format(fmt, "after", "chapters", chap.getLong(book));44
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Field chars = c.getDeclaredField("characters");47
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out.format(fmt, "before", "characters",49
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Arrays.asList(book.characters));51
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String[] newChars = { "Queen", "King" };53
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chars.set(book, newChars);55
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out.format(fmt, "after", "characters",57
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Arrays.asList(book.characters));59
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Field t = c.getDeclaredField("twin");62
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out.format(fmt, "before", "twin", book.twin);64
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t.set(book, Tweedle.DUM);66
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out.format(fmt, "after", "twin", t.get(book));68
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// production code should handle these exceptions more gracefully71
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} catch (NoSuchFieldException x) {73
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x.printStackTrace();75
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} catch (IllegalAccessException x) {77
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x.printStackTrace();79
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}81
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}83
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}85
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/*88
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* Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.90
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*92
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* Redistribution and use in source and binary forms, with or without94
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* modification, are permitted provided that the following conditions96
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* are met:98
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*100
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* - Redistributions of source code must retain the above copyright102
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* notice, this list of conditions and the following disclaimer.104
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*106
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* - Redistributions in binary form must reproduce the above copyright108
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* notice, this list of conditions and the following disclaimer in the110
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* documentation and/or other materials provided with the distribution.112
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*114
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* - Neither the name of Oracle or the names of its116
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* contributors may be used to endorse or promote products derived118
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* from this software without specific prior written permission.120
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*122
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS124
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* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,126
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR128
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR130
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