Java by API/java.lang.reflect/AccessibleObject

AccessibleObject: setAccessible(boolean flag)

/*
Before: [a=21.25, b=54.5, c=5665, d=2043, e=3121, f=1019]
After: [a=21.25, b=54.5, c=0, d=0, e=0, f=0]
*/
/*
 *
 * This software is granted under the terms of the Common Public License,
 * CPL, which may be found at the following URL:
 * http://www-124.ibm.ru/developerworks/oss/CPLv1.0.htm
 *
 * Copyright(c) 2003-2005 by the authors indicated in the @author tags.
 * All Rights are Reserved by the various authors.
 *
########## DO NOT EDIT ABOVE THIS LINE ########## */
import java.lang.reflect.Field;
/**  
 * Demonstrates how to set public field objects.
 *
 * @author 
 * @version $Revision: 1.3 $
 */
public class HiddenFieldModification {
  /** 
   * Sets all int fields in an object to 0.
   *
   * @param obj The object to operate on.
   *
   * @throws RuntimeException If there is a reflection problem.
   */
  public static void initIntFields(final Object obj) {
    try {
      Field[] fields = obj.getClass()
                        .getDeclaredFields();
      for (int idx = 0; idx < fields.length; idx++) {
        if (fields[idx].getType() == int.class) {
          fields[idx].setAccessible(true);
          fields[idx].setInt(obj, 0);
        }
      }
    } catch (final IllegalAccessException ex) {
      throw new RuntimeException(ex);
    }
  }
  /** 
   * Demo Method.
   *
   * @param args Command line arguments.
   */
  public static final void main(final String[] args) {
    SomeNumbers value = new SomeNumbers();
    System.out.println("Before: " + value);
    initIntFields(value);
    System.out.println("After: " + value);
  }
}
class SomeNumbers {
  /** A demo double. */
  public double a = 21.25d;
  /** A demo float. */
  public float b = 54.5f;
  /** A Demo int */
  public int c = 5665;
  /** Another demo int. */
  public int d = 2043;
  /** Another demo int. */
  protected int e = 3121;
  /** Another demo int. */
  private int f = 1019;
  /** 
   * @see java.lang.Object#toString()
   */
  public String toString() {
    return new String("[a=" + a + ", b=" + b + ", c=" + c + ", d=" + d + ", e=" + e
                      + ", f=" + f + "]");
  }
}