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

1. Java
2. Reflection
3. Enum

Deal with Enum Type in reflection

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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();
    }
  }
}

 

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