Deal with Enum Type in reflection : Enum « Reflection « Java






Deal with Enum Type in reflection

/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import static java.lang.System.out;

import java.lang.reflect.Field;
import java.util.Arrays;

enum Tweedle {
  DEE, DUM
}

public class Book {
  public long chapters = 0;
  public String[] characters = { "Alice", "White Rabbit" };
  public Tweedle twin = Tweedle.DEE;

  public static void main(String... args) {
    Book book = new Book();
    String fmt = "%6S:  %-12s = %s%n";

    try {
      Class<?> c = book.getClass();

      Field chap = c.getDeclaredField("chapters");
      out.format(fmt, "before", "chapters", book.chapters);
      chap.setLong(book, 12);
      out.format(fmt, "after", "chapters", chap.getLong(book));

      Field chars = c.getDeclaredField("characters");
      out.format(fmt, "before", "characters", Arrays.asList(book.characters));
      String[] newChars = { "Queen", "King" };
      chars.set(book, newChars);
      out.format(fmt, "after", "characters", Arrays.asList(book.characters));

      Field t = c.getDeclaredField("twin");
      out.format(fmt, "before", "twin", book.twin);
      t.set(book, Tweedle.DUM);
      out.format(fmt, "after", "twin", t.get(book));

      // production code should handle these exceptions more gracefully
    } catch (NoSuchFieldException x) {
      x.printStackTrace();
    } catch (IllegalAccessException x) {
      x.printStackTrace();
    }
  }
}

 








Related examples in the same category

1.Is it an enum
2.Get declared methods for enum class
3.Enum type as class
4.Enum Spy
5.Deal with enum type and its method
6.Deal with enum type field
7.Get and set value of a Enum type field